The Trump family’s new crypto token surged in just two days to become one of the most valuable forms of digital currency in the world, creating the potential for a multibillion-dollar payout to the family but also generating a storm of questions about the conflicts of interest the new venture creates.

President-elect Donald J. Trump announced the launch of the new token, $Trump, on Friday night as hundreds gathered for a crypto-inspired inauguration ball not far from the White House.

The venture won praise by some as a sign of how digital currencies are now going mainstream in the United States.

But economists and even some longtime crypto investors said the new digital coin, known as a memecoin, might also emerge as a landmark moment in the speculative history of crypto trading and the potential dangers it poses to the financial system. Memecoins are a type of cryptocurrency tied to an online joke or a celebrity mascot.

“If people want to gamble, I don’t really care,” said Lee Reiners, a former Federal Reserve economist who is now a lecturer for a center studying global economic markets at Duke University. “What I care about is when this crypto bubble bursts — and it will burst — it will end up impacting people across the economy even if they don’t have direct investment in crypto. And this new coin is making it worse.”

Eric Trump, one of Mr. Trump’s sons, who helped launch the token, declined to comment on Sunday.

At least on paper, the Trump tokens in the market as of Sunday late afternoon had a total trading value of nearly $13 billion, and a total of $29 billion worth of trades had taken place in just two days. That calculation is based on the nearly $64 value of each of the 200 million tokens issued, according to CoinGecko, an industry data tracker.

This suggests, as of Sunday, that Mr. Trump’s coin was the 19th most valuable form of cryptocurrency in the world, the CoinGecko tally indicated.

The Trump affiliates appear to control another 800 million tokens that, at least hypothetically, could be worth as much as $51 billion — a total that would make Mr. Trump one of the richest people in the world.

Before the coin started trading, Forbes had listed Mr. Trump’s net worth as $6.7 billion, most of that coming from Trump Media and Technology Group, another speculative venture the Trump family helped start, which runs the money-losing social media platform Truth Social.

The Trump family late on Sunday moved to add a second new crypto token, this one called $Melania, with Mr. Trump and Melania, his wife, both promoting it on Truth Social, just as Mr. Trump was about to start a rally in Washington celebrating his inauguration.

“The official Melania Meme is live!” the social media posting said.

That move then coincided with a dive in the value of Mr. Trump’s own token, dropping to as low as $41, before starting to rise again, as doubts appeared to emerge over just how valuable these new tokens would actually be. Mr. Trump did not appear to be deterred.

“Bitcoin has shattered one record after another,” Mr. Trump said at his rally, referring to another form of cryptocurrency. He added during his remarks that “these are all investments that are only being made because we won the election.”

But Mr. Trump’s newfound crypto wealth would likely vaporize if he moved to sell his trove of coins. New cryptocurrencies often shoot up in price, making traders billionaires on paper, only to collapse when the coins’ holders start selling.

That is especially true of memecoins, which are prone to rapid swings in price as their internet popularity fluctuates. Prices can also vary across platforms, making it difficult to pin down a coin’s actual value. In 2021, one of the first memecoins, a dog-based digital currency called Dogecoin, minted millionaires overnight, only to lose much of its value just as quickly.

The launch of the Trump memecoin caught many of the industry’s power brokers off guard.

When the president-elect announced the coin on Friday night, hundreds of the most influential executives in the industry were drinking cocktails and singing along to Snoop Dogg at an inauguration party in Washington dubbed the Crypto Ball. (One executive who attended the ball said he was “annoyed” that trading in the coin had begun while the industry’s leaders “weren’t paying attention,” making it difficult for them to profit.)

Nonetheless, some traders have already cashed in.

Within a minute of the coin’s launch, a crypto trader had accumulated a $1 million position, according to an analysis of public transaction data by the crypto data firm Bubblemaps, which posted its findings on social media.

The coin’s price surged, and the trader’s account soon sold off holdings worth $20 million. The analysis prompted speculation on social media about whether an insider with advance knowledge of the coin’s launch had been able to make quick profits. (Bubblemaps did not immediately respond to a request for comment.)

Conor Grogan, a director at Coinbase, one of the largest trading platforms in the United States, estimated in a social media post that as of Saturday, the Trump team had made $58 million in fees from all of the $Trump sales — even without selling its own reserve of tokens to the open marketplace.

It also appears that the Trump team may be transferring some of its tokens onto an overseas trading platform called Bybit, which is not allowed to execute trades in the United States, Mr. Grogan noted. Bybit has recently been the focus of enforcement actions by international cryptocurrency regulators.

The Trump coin’s launch immediately created new opportunities for executives, crypto traders and even major companies to curry favor with the Trump administration.

Anyone can spin up a memecoin for a few dollars, and the vast majority of the tokens are not available to buy and sell on mainstream digital currency marketplaces, which often focus on larger, more established coins. But within hours of Mr. Trump’s announcement, the crypto exchange Kraken began offering the new coin, and Coinbase, the largest exchange in the United States, said it would also list it.

Coinbase and Kraken are fighting lawsuits filed by the Securities and Exchange Commission, which conducted a wide-ranging crackdown on crypto firms during the Biden administration. The companies are among a large group of crypto firms that stand to benefit from the more relaxed approach to tech regulation that Mr. Trump promised on the campaign trail.

A onetime crypto skeptic, Mr. Trump embraced the digital currency industry last year, giving a speech at a major industry conference in which he promised to turn the United States into the “crypto capital of the planet.”

After winning the election, Mr. Trump made a series of moves that appear poised to benefit the crypto industry. He chose someone to lead the S.E.C. who has a track record of working closely with crypto companies, and tapped the venture capitalist David Sacks, a digital currency enthusiast, to oversee crypto and artificial intelligence policy for his administration.

At the Crypto Ball, Mr. Sacks announced from the stage that “the reign of terror against crypto is over, and the beginning of innovation in America for crypto has just begun,” according to a video posted on social media by Eric Trump.

The president-elect’s family was personally invested in the crypto market even before the memecoin launched. In September, he and his sons helped start a crypto business, World Liberty Financial, that also has a digital coin associated with it, WLFI.

World Liberty is not directly owned by the Trumps. But Mr. Trump is a promoter of the venture, and he receives a cut of the profits from token sales.

For the most part, the crypto industry has responded enthusiastically to Mr. Trump’s crypto ventures. But some executives expressed concern this weekend that the memecoin launch would end up hurting amateur traders.

A popular crypto podcaster called it a “gratuitous cash grab” that would be “bad for humanity.” Erik Voorhees, a prominent Bitcoin investor, wrote on social media that the memecoin was “stupid and embarrassing.”

Still the Trump family’s embrace of cryptocurrencies shows no sign of slowing down.

“It’s time to celebrate everything we stand for: WINNING!” Mr. Trump wrote on Friday as he announced the birth of the new crypto token. “Join my very special Trump Community. GET YOUR $TRUMP NOW.”