SAN FRANCISCO — This past week, a trading card featuring the quarterback Tom Brady sold for a record $1.3 million. The total value of the cryptocurrency Bitcoin hit $1 trillion. And Christie’s sold a digital artwork by an artist known as Beeple for $69.3 million after bids started at just $100.

These seemingly singular events were all connected, part of a series of manias that have gripped the financial world. For months, professional and everyday investors have pushed up the prices of stocks and real estate. Now the frenzy has spilled over into the riskiest — and in some cases, wackiest — assets, including digital ephemera and media, cryptocurrencies, collectibles like trading cards and even sneakers.

The surges have been driven by a unique set of conditions. Even as millions were laid off in the pandemic, many people’s bank accounts flourished, flush from stimulus checks and government cash infusions into the economy. But while people accumulated more money, traditional investments like stocks and bonds became less attractive.

So many got creative and, bored in the pandemic, took on more risk. Often, they were egged on by online communities on Reddit and Discord, where the next big investments were hotly debated. They also turned to tech tools like the trading app Robinhood and the cryptocurrency platform Coinbase, which allowed them to buy and trade different items with the click of a button.

That has now led to mini-bubbles across a wide variety of esoteric categories, making once-obscure acronyms like SPACs and NFTs practically as ubiquitous as the S&P. It has also fed ferocious demand for this week’s public listings of companies like the gaming site Roblox and the South Korean e-commerce company Coupang, as well as for shares of the video game retailer GameStop and other so-called “meme” stocks.

“It’s just a pent-up cycle where the money has nowhere to go, so it’s doing stupid things,” said Howard Lindzon, an investor, entrepreneur and market commentator.

The manias, which have erupted at a time of deep economic pain, have introduced a large amount of risk to many investors. Some people have already racked up staggering losses on Robinhood, which has been accused of encouraging gambling-like behavior. Other assets, like Bitcoin, are volatile, while sneakers and NFTs are so new and hyped-up that it is difficult to know what they will be worth over time.

For now, the bubble-upon-bubble behavior does not appear to pose a systemic risk to the broader financial system. But some investors said they were uneasy.

“Most people are cheering, but at the same time, shaking their heads and going, when is the bust coming?” said Jane Leung, the chief investment officer at SVB Private Bank.

One of those who bought into the frenzy was Matthew Schorr, 35, a lawyer in Cherry Hill, N.J. For years, he has been on the lookout for hot investments, but lost interest in the stock market and abandoned Bitcoin after his friends dismissed the cryptocurrency as “fake money.” He now regrets that because the value of a single Bitcoin has soared above $57,000, meaning the eight Bitcoin he paid for a Domino’s pizza in 2011 would be worth more than $450,000 today.

Mr. Schorr did not want to miss out again. So starting in January, he spent $5,000 to buy 351 videos from NBA Top Shot, a site for trading basketball highlight clips, after he saw social media chatter about them selling for tens of thousands of dollars. The value of those clips has now soared to $67,000, according to Momentranks.com, which tracks the sales.

The clips are a type of investment known as NFTs, or nonfungible tokens, which have taken off in music, art and sports. The digital tokens use networks of computers to prove that a digital item like a video, image or song is authentic, giving the item a value — at least in the eyes of the person buying it. Some liken NFTs to digital trading cards. (The creators of the underlying works typically retain the copyright.)

Skeptics consider NFTs among the most questionable of assets, since an NFT image can be endlessly copied and shared. Still, enough people are convinced of the value of authenticating tokens that they have dovetailed with another market-propelling phenomenon, FOMO, or “fear of missing out.”

“I’m trying to keep my finger on the pulse and not let myself fall behind again,” said Mr. Schorr, who spends as much as five hours a day researching the market and chatting with fellow collectors on Discord. “That sort of return over six weeks is completely unheard-of in any financial vehicle.”

Last month, NBA Top Shot crossed $232 million in total sales since it started last year — including $47.5 million in sales on a single day.

“I think there is another 100X from here,” said Roham Gharegozlou, chief executive of Dapper Labs, the company that partnered with the NBA to create NBA Top Shot. “There is so much demand.”

Much of this investment momentum began last year, after the coronavirus spread and the global economy went into free fall. In response, the United States slashed interest rates, bought government bonds and passed stimulus packages. Germany, Brazil, Japan and other countries took similar actions.

Those moves had a twofold effect of increasing the amount of money in the global financial system while also encouraging people to spend. Deposits in U.S. bank accounts hit $16.45 trillion last month, more than $3 trillion above the level in January 2020, according to Federal Reserve data. The interest rate set by the Federal Reserve has been near zero since last March.

Low interest rates made traditional investments like bonds less attractive, while stocks, which have risen for a decade, became even more expensive. That was when more people started investing in nontraditional assets.

With NFTs, the hysteria escalated quickly. Last month, an NFT GIF of Nyan Cat, which shows an animated flying cat with a Pop-Tart body, sold for roughly $580,000. Other artists, including Grimes and Steve Aoki, began reaping millions of dollars from their digital artwork. Then on Thursday, Beeple, whose real name is Mike Winkelmann, sold his “Everydays — The First 5000 Days” NFT for a stunning $69.3 million.

Slava Rubin, founder of Vincent, a start-up that helps people find investments in alternative assets such as wine, collectibles and litigation finance, said his site has attracted tens of thousands of users. Last month, he said, interest in NFTs jumped by 44 percent and collectibles by 33 percent, making them the fastest-growing categories on the site.

“The public is really leaning into these new ways of thinking about how to invest, whether it’s for pure profit, a hobby or based on nostalgia and interest,” he said.

This month, the electronic musician 3lau made $11.7 million selling NFTs related to one of his previously released albums. Buyers not only received the digital tokens representing the authentic version of the album, but also got access to new music and a limited edition vinyl copy.

3lau, whose real name is Justin Blau, said he was “blown away” by the price and how it showed support for the new market. “People are excited about storing value in a medium that gives them emotional value,” he said.

Investors have also gravitated to SPACs, which are “special purpose acquisition companies.” Many have thrown money at these financial vehicles, which trade on the public market, even though they are shell companies with no operations. Instead, their creators promise shareholders that they will find a private company to merge with, effectively taking the company public.

SPACs have been so plentiful this year that they outnumber new listings from real companies by nearly four to one, according to Renaissance Capital, which tracks public listings. Some investment firms have rolled out three or four new SPACs at a time, while celebrities and sports stars including Shaquille O’Neal, Serena Williams, Colin Kaepernick and Ciara have formed their own.

Often, the SPACs merge with companies that have never made a dollar. Two electric air taxi companies that do not expect any revenue for years — Joby Aviation and Archer Aviation — announced SPAC deals last month that valued them at $6.6 billion and $3.8 billion respectively.

Sneaker reselling has also exploded. On StockX, a marketplace comparable to eBay where people buy and sell sneakers and other collectibles, shoe sales in January were nearly double that of a year ago, said Scott Cutler, the company’s chief executive. That growth was helped by the sale of a famous style of Nike Dunks — the SB Low Staple NYC Pigeon — for a record $33,400 that month.

Younger generations want to invest in things that are culturally relevant and financially sound, Mr. Cutler said, and sneakers are “actually a far more stable investment than you may assume.”

Trading card sales have taken off, too. The price of mint condition cards on StockX jumped to an average $775 in January from $280 a year ago. This week’s $1.3 million sale of the Tom Brady card — one of 100 of its kind from his rookie season — followed a similar Brady card going for $555,988 in January.

Predicting when and how the party will end is anyone’s guess. Some anticipate that wide vaccine distribution and a return to normal life post-pandemic will bring about a Roaring Twenties-style era of prosperity. While that decade ended in a devastating crash, the euphoria lasted years.

That period was “pretty wild” and led to “pretty rapid technological change,” said Laura Veldkamp, a finance professor at Columbia Business School. “And there was lots of money to be made.”