In early December, Donald J. Trump put on a tuxedo and boarded the private jet of a scrap-metal magnate and crypto-miner for a short flight across Florida, touching down at an airport in Naples. There, a long red carpet marked the pathway into a Christmas-decorated hangar filled with supporters of Mr. Trump who had paid $10,000 to $30,000 for the privilege of attending a party and taking a photo with him.

The event had all the trappings of a typical high-end fund-raiser: a giant American flag, a lectern, chandeliers and an open bar. Frank Stallone’s band provided the music; an anti-Biden “Let’s Go Brandon” banner hung from the rafters.

But the money raised did not go to Mr. Trump’s political operation. Instead, Mr. Trump’s share of the evening’s proceeds went straight into his pocket, according to a person familiar with the arrangement.

Multiple attendees said they bought their tickets from a private company, Whip Fundraising, whose founder, Brad Keltner, has asserted that “the lion’s share” went to charity. But the website advertising the event listed no charitable cause. And Mr. Keltner, reached by phone, declined to discuss how money was distributed.

In the year since Mr. Trump has left the White House, he has undertaken a wide-ranging set of moneymaking ventures, trading repeatedly on his political fame and fan base in pursuit of profit. Much as he did while in the White House, Mr. Trump has thoroughly blurred the lines between his political ambitions and his business interests.

He has gone on an arena tour with the former Fox News host Bill O’Reilly, where a backstage “V.I.P. package” sold for more than $7,500. He has published a $75 coffee-table book, after being paid a multimillion-dollar advance by a new publishing company co-founded by his eldest son. He has turned an online Trump store into a MAGA merchandiser, with his company sending marketing missives to people on his 2020 campaign’s email list.

That store is now selling red “Make America Great Again” hats for $50 each — a $20 markup from the price currently offered by his political action committee — with all proceeds going to a Trump-owned company.

His wife, Melania, has gotten into the act, too, auctioning off online collectibles and scheduling her own big-ticket event in Naples this April, a “tulips and topiaries high tea,” with V.I.P. packages reaching $50,000 and an undisclosed portion going to charity.

For Mr. Trump, the monetization of his post-presidency represents a return to his roots. He expertly leveraged his celebrity as the host of “The Apprentice” and his image as a decisive businessman to build credibility when he first entered politics. Now, he is executing the same playbook, only in reverse: converting a political following that provided hundreds of millions of dollars in small campaign contributions into a base of consumers for all things branded Trump.

There are grandiose enterprises, such as a fledgling social-media company, whose billion-dollar market capitalization is largely predicated on Mr. Trump’s direct personal involvement. And there are smaller ones, like remodeling the lobby bar of Trump Tower in Manhattan and renaming it the 45 Wine and Whiskey Bar — where specialty cocktails range in price up to, yes, $45 (that one comes with two “American beef sliders”) and can be sipped in dark velvet chairs surrounded by Mr. Trump’s black-and-white presidential portraits and paraphernalia.

“You come here, you drink Trump,” said Daniel Popescu, a 79-year-old architect and a bar regular, whose typical order is a $20 glass of Trump Blanc de Blanc sparkling wine. He hailed Mr. Trump on a recent evening as “the best president this country has ever had.”

“For a billionaire to give up his life to do good for the country,” Mr. Popescu said with a shake of his head and a sip, “it’s unbelievable.”

Other past presidents have cashed in financially after leaving the White House. Barack and Michelle Obama reportedly sold a joint book deal for $65 million. Bill and Hillary Clinton’s speechmaking after leaving the White House was estimated to have netted them $153 million by the spring of 2015, when Mrs. Clinton announced her own run for president. George W. Bush has been a mainstay on the speaking circuit, too.

But no former president has been more determined to meld his business interests — from chocolate bars to real estate to a tech start-up — with a continuing political operation and capitalize on that for personal gain.

Taylor Budowich, a spokesman for Mr. Trump, noted that Mr. Trump had been wealthy before seeking public office. “After sacrificing considerably to lead our nation, there continues to be unprecedented demand for President Trump, his thoughts and his products, unlike anything politics has ever seen,” Mr. Budowich said.

Eric Trump, the executive vice president of the Trump Organization, added in an interview that direct consumer sales and Mr. Trump’s public appearances were worth a trivial amount of money compared with the organization’s real estate deals and other major ventures.

“We have had an exceptional year as a company,” he said.

Blurred lines between profit and politics

Any division between Mr. Trump’s business and his political operation can be hard to discern.

At his first campaign-style rallies of 2022, in Arizona and Texas, giant television screens paid for by Mr. Trump’s PAC advertised his $75 picture book. His political operation has also promoted the book in emails to his supporters, as has his official post-presidential office, which also issued a recent statement (“Check it out!”) promoting a Trump property in Miami.

Lawrence M. Noble, former general counsel at the Federal Election Commission, said that the combination of ways that Mr. Trump had monetized his life after the White House, while remaining intimately involved in Republican politics and a possible future candidate himself, had created ethical questions unlike any post-presidency in modern times.

“The thing that is different about Trump is the making-money part seems to have permeated everything,” Mr. Noble said. “There is this appearance, at least, that he is always thinking: How can I make a profit off of this?”

Mr. Trump faced similar questions while president, as he frequently promoted, patronized and profited from his private properties, including internationally. Watchdogs who worried then about his selling access remain concerned.

“It is wrong for influence and power in this country to be sold for personal profit,” Mr. Noble said.

Out of office, Mr. Trump faces few formal limits on his business dealings, though if he were to run again in 2024, some of his financial activity would be revealed on future disclosures. His political action committees have even fewer constraints than his re-election campaign account did.

In 2021, Mr. Trump’s political committees spent more than $600,000 on Trump properties for rent, meals, meeting expenses and hotel stays, records show. His PAC continued to make monthly $37,541.67 rent payments to Trump Tower Commercial LLC.

The roughly $375,000 the PAC paid in Trump Tower rent was more than the total of $350,000 that Mr. Trump’s group donated to the scores of federal and state-level political candidates he endorsed in 2021.

Many of those candidates, in turn, redirected funds back to Mr. Trump, holding lavish events at his properties. Herschel Walker, the former football player whom Mr. Trump recruited to run for Senate in Georgia, spent more than $135,000 at Mar-a-Lago, Mr. Trump’s private Florida club. The Republican National Committee forked over $175,000 for a fund-raiser there in the spring.

Mr. Trump’s PAC made two $1 million donations to conservative nonprofits in 2021: the America First Policy Institute and the Conservative Partnership Institute. Both also hosted big events at Mar-a-Lago.

Marketing MAGA to the masses

After years of slapping his name, for a price, on everything from steaks to water bottles to golf courses, Mr. Trump has found a big new market for lower-priced goods like hats, T-shirts and books.

The new push to capitalize on Mr. Trump’s name and brand echoes what he has done for decades with his real estate company, whose holdings now include six hotels in the United States and more than a dozen golf clubs.

The real-estate business has, for the most part, been shrinking, with the Trump family selling off, terminating or being pushed out of hotel contracts in Washington, Toronto, New York City, Vancouver and Panama in recent years

As Mr. Trump left office, his company was going through a challenging time, with a bad year at its remaining hotels because of the coronavirus pandemic and the decision by several blue-chip vendors — including its law firm, real estate broker and two banks — to stop doing business with the family after the Jan. 6 attack on the Capitol.

But the golf business has benefited from a surge in play during the pandemic, with revenues even at the Trump golf course near Los Angeles, a Democratic stronghold, jumping by 50 percent since 2019, according to tax records.

Mr. Trump’s business practices are the subject of investigations in New York by the Manhattan district attorney and the state attorney general’s office, inquiries that Eric Trump says are politically motivated.

In an interview, the younger Mr. Trump accused Democratic politicians like Attorney General Letitia James of New York of seeking political power by promising to go after his father.

“​Letitia James campaigned on the promise of harassing and suing Donald Trump,” he said. “It’s prosecutorial misconduct and it’s something you would find in a third world country.”

In Miami, the Trump family has announced plans to expand the Trump National Doral, long one of its biggest sources of revenue, by adding high-rise luxury condos.

On a far bigger scale, the Trump Media & Technology Group, which is behind the new social media company, has raised more than $1 billion. Bankers for the company dangled an unusual perk: Invest at least $100 million, get a phone call from the former president. Later, the price of such a call came down to $50 million.

But for the most part, since Mr. Trump left office, his business has focused on appealing to Middle America, not buyers of luxury condos or multimillionaire investors.

His four-stop tour with Mr. O’Reilly sought to fill arenas at $100 a ticket. Mr. O’Reilly pushed back on reports of empty seats by disclosing that “gross receipts” on the first show alone were $2 million. A tour organizer did not respond to requests for comment.

On sale at the events was Mr. Trump’s coffee-table book, which the former president has said is nearing 250,000 copies sold. His multimillion-dollar advance from the publishing company, first reported by The Washington Post, was confirmed by a person familiar with the arrangement; The Post also reported that Mr. Trump has delivered paid speeches since leaving office.

The book’s sales are scarcely spectacular: The tell-all from his niece, Mary Trump, had sold 950,000 copies by the day it went on sale. But Mr. Trump’s picture book is priced far higher. Signed copies went for $229.99 and quickly sold out.

Sergio Gor, a co-founder of Winning Team Publishing with Donald Trump Jr., called the book a success and said he was “in discussions” to acquire the rights to the former president’s next one.

Winning Team Publishing announced its second author this week: Charlie Kirk, the leader of Turning Point USA, a conservative youth group that holds its winter gala at Mar-a-Lago. Tax records for the most recent year available show the group spent nearly $280,000 there on food and beverages.

Mr. Trump’s for-profit store, meanwhile, has added a “MAGA collection,” and sells items like a $95 Mar-a-Lago Christmas ornament, that it is marketing to supporters of Mr. Trump’s 2020 campaign through email lists rented from the Trump political operation and maintained by Brad Parscale, Mr. Trump’s former campaign manager.

Donald Trump Jr., for his part, operates another online store, selling proudly provocative clothes, like shirts that say, “Guns Don’t Kill People / Alec Baldwin Kills People” — a reference to the actor’s movie-set shooting last year. After the acquittal of Kyle Rittenhouse, the teen who shot and killed two people during the unrest in Kenosha, Wis., the store briefly promoted a new sweatshirt: “In a World Full of Alecs, Be a Kyle.”

Collectibles and ‘high tea’

Mrs. Trump, too, has found ways to monetize her ties to Mr. Trump, including through a series of online sales. In January, she put up for auction a digital portrait of her by a French artist, a print of the portrait and a white hat she once wore at the White House while meeting the president of France.

Her plan to maximize the sales price by accepting payments only in cryptocurrency appears to have backfired, however: The crash in cryptocurrency prices in January reduced the planned opening-bid price of $250,000 to about $170,000 on the final day of the auction.

The auction drew just seven bids, according to electronic records, which also suggest that the winning bid was made by the auction’s sponsors.

Shortly before the auction, Mrs. Trump joined the conservative social-media site Parler. Her first posts were about Pearl Harbor Day and deadly tornadoes in Kentucky, but she began frequently posting about the online auction.

On Wednesday, Parler announced a deal with Mrs. Trump whose financial terms were not disclosed. In a statement, she said she would provide the site exclusive content “to inspire others” and promote a series of future online auctions of “collectibles” like the hat she wore at the White House.

Mrs. Trump is now selling tickets to the April “high tea,” with organizers saying that some of the profits will benefit an initiative of her “Be Best” endeavor called “Fostering the Future,” meant to provide computer-science scholarships to young people who have been in foster care.

There was no indication of how much of the proceeds Mrs. Trump herself intended to pocket. Florida requires any organization that raises charitable contributions in the state to register. No charity with the name “Fostering the Future” or “Be Best” is registered in Florida.

Asked about the solicitation, officials at the Florida agency that oversees charitable fund-raising said they also could not find evidence of the required state registration and had opened an inquiry as a result.

“Consumer Services Division is currently investigating whether this event involves an entity operating in violation of Chapter 496, Florida Statutes,” Erin M. Moffet, an agency spokeswoman, said in a statement, referring to the state law requiring charities to register before soliciting money.

Mrs. Trump did not respond to questions about the state requirements.

The company behind the “high tea” event, Whip Fundraising, also organized Mr. Trump’s holiday party in Naples, Fla., in December, where several attendees said that guests were asked to put their phones in small magnetic pouches while Mr. Trump spoke to limit the shooting of unauthorized videos or photos.

Beyond the ticket price, the event generated revenue from an auction of items including a bottle of Pappy Van Winkle bourbon with a portrait of Mr. Trump painted on the label, and a signed photograph of Mr. Trump holding a Bible across the street from the White House after the police cleared protesters from the area in June 2020.

Mr. Keltner, the owner of Whip Fundraising, said that events like the one in Naples raised large sums for charity but declined to discuss the specifics of any events with Mr. Trump.

It was Mr. Keltner who arranged the flight for Mr. Trump to Naples, on the plane of Adam Weitsman, a crypto-mining investor who also owns a scrap-metal company in New York. Mr. Weitsman said he flew Mr. Trump and the former first lady as a “favor” to Mr. Keltner.

He said he did not have to pay for the privilege.

“I just gave them a ride,” Mr. Weitsman said, adding that the Trumps were very nice and respectful.

Steve Eder and Rachel Shorey contributed reporting.