Nvidia is up 2,000Percent since 2019. These WSJ readers invested early.

The stock has more than doubled so far this year, making Nvidia the best performing member of the S&P 500 in 2024, despite recent wobbles. Nvidia’s chips power the artificial-intelligence systems that have exploded in popularity in the past couple of years. Investors have rushed to own a piece of a company that they hope is at the vanguard of widespread AI adoption.

Nvidia briefly became the world’s most valuable company in June, a title that seemed almost unimaginable five years ago, when it didn’t crack the top 20. Even with a roughly 9% pullback from its June high, the stock is up about 700% since the end of 2022, split-adjusted. Nvidia’s shares have had a total return of more than 500,000% since the company’s initial public offering in 1999. Its market value is hovering near $3 trillion.

Shareholders are awaiting Nvidia’s quarterly earnings report slated for Wednesday, which could be the spark for the stock’s next leg higher—or a reality check to send shares tumbling.

Around 30% of Nvidia shares are owned by individual investors and smaller asset managers, according to FactSet, roughly in line with other megacap tech stocks like Apple and Microsoft.

For some everyday investors, the rally has allowed them to retire early, travel, pay off debt, donate to their favorite causes or save up for a house or a second home. For others, the money is secondary. They savor the thrill of picking a winner—and beating other investors to the punch.

Jim Woods, Paducah, Ky.

Jim Woods first learned about Nvidia from an article in The Wall Street Journal in 1999, months after the company went public. The profile of co-founder and Chief Executive Jensen Huang piqued Woods’s interest and led to more research. He thought the computer-chip business would become a booming industry and decided to invest in Nvidia in 2000.

“I’m always looking for a company that is small in a market that I think is going to grow," said Woods, a 70-year-old orthodontist.

Nvidia had another selling point for Woods: Huang had lived in Kentucky briefly after immigrating from Taiwan to the U.S. in his youth.

“I just felt a connection there," Woods said.

Woods put about $65,000 into Nvidia, buying 250 shares at the time. Through reinvesting dividend payouts and various stock splits, that position has turned into about 124,000 shares—worth around $15 million.

“It’s been a hard stock to hold," Woods said. “If you’re not willing to ride all the ups and downs it has gone through, you would have never gotten to this point."

Nvidia slumped 50% in 2022, when rising interest rates weighed on tech stocks. The stock also logged a 76% pullback in 2008 and an 83% fall in 2002.

He has never sold any shares but is considering trimming his position in the coming months. He may put some of that money into two-month Treasurys. He doesn’t plan to fully liquidate the Nvidia position, partly because of the capital-gains tax that would await.

Woods said he is fortunate that he and his wife don’t need the money. He expects that his daughter will likely inherit a significant portion of his Nvidia investment, and he is also interested in creating a charitable fund.

Mark Hatala, Kirksville, Mo.

College students are a great resource for stock picks; just ask Mark Hatala, a professor of psychology at Truman State University. He first invested in Nvidia two decades ago after learning about the chip maker from a student who loved playing videogames and building his own computers. Nvidia’s graphics cards were considered best in class among the gaming crowd.

Hatala put about $2,000 into Nvidia shares around 2002. He bought more stock a few years later and trimmed and added to his position over the following years. He never sold out entirely and hasn’t taken any profits since 2008. He said his Nvidia investment is worth north of $1 million.

“It’s like winning a lottery," Hatala said.

The 58-year-old plans to retire early next year, in part because of the feeling of financial security he has from Nvidia’s massive stock-price rally. He plans to split his time among Missouri, France, Japan and the Philippines, while doing personal research and writing books.

“It’s just the freedom to do whatever I want," he said, “which I think is what happiness and joy truly are."

Matthew Harris, Houston, Texas

Matthew Harris spent his summers in high school working as a lifeguard, saving up about $20,000. Around 2018, he decided to invest that money in the stock market.

He went all-in on technology stocks. His father invested in Apple early, inspiring him to find the next tech behemoth. After doing some research on chip makers, he put about $4,000 into Nvidia shares, impressed by the company’s early commitment to artificial intelligence.

“It was kind of risky, but that’s what you need to do when you’re young," said Harris, who is 25 years old.

He never sold that initial investment and has added to his position since. In all, his Nvidia holding is now in the six figures.

“It’s pretty surreal. Seeing my portfolio go up is pretty life-changing," he said, expressing his appreciation for Huang’s leadership of the company.

Harris recently graduated from law school and took the bar exam last month. He may use his Nvidia shares to help buy a house down the line.

His reaction to cynics who think the AI boom is a repeat of the dot-com bubble?

“They are just people who are late to the party," he said.

Deborah Lee, New York City

Nvidia is the biggest investment in Deborah Lee’s self-directed stock portfolio. She describes it as a blessing and a curse.

Lee, who works in financial services and is 53 years old, first bought Nvidia shares in 2018 after researching the videogame industry.

It was a relatively small position for her then, making up less than 4% of her portfolio by the end of 2018. Now, Nvidia is around a third of the portfolio, worth six figures. That is even after taking some profits in the past two years. Lee put the money toward a real-estate investment and paying off some debt.

“I picked a winner relatively early and that feels good," said Lee.

She says she believes Nvidia can continue to grow in the next year or two but is uncomfortable with the size of the position in her portfolio. Even relatively small moves in Nvidia’s share price can have an outsize influence on the direction of her portfolio.

Lee plans to continue trimming her Nvidia position by about 5% at a time. She would like to move that money into new stocks that could become the next Nvidia.

“I don’t expect Nvidia to go up another 25 times," she said. “Being a $3 trillion company, is it going to be a $6 trillion company next year? I don’t think so."

Munusamy Venkataraman, Darien, Ill.

Munusamy Venkataraman doesn’t remember when he first invested in Nvidia, but he sure remembers that he sold most of his position before 2015. He estimates he owned about 300 shares at the time, which would have multiplied after a four-for-one stock split in 2021 and a 10-for-one split this year.

“I made a mistake by selling," he said. “But nobody knew."

Venkataraman, 81, held on to some of his original Nvidia shares and bought more in 2017. With dividend reinvestment and the stock splits, he now owns about 600 shares. In each of his transactions, he bought Nvidia for under $4 a share on a split-adjusted basis. The stock recently closed at $123.74, making his position worth around $74,000.

The retired immunologist doesn’t plan to sell his Nvidia stock. In fact, he’s looking to buy more, one or two shares at a time when he sees opportunities.

“It’s only the beginning," he said of AI technology. “We don’t know where we’re going to end."

Alan Daut, Altoona, Iowa

Nvidia first came across Alan Daut’s radar through Jim Cramer’s “Mad Money" program on CNBC. After watching the stock for about a year, Daut used some profits from a different stock sale to buy shares of Nvidia in 2019.

The stock has risen roughly 3,000% since that initial investment, he said. He has sold portions of his position since then, but isn’t planning to sell out completely. He now owns about 900 shares of Nvidia, worth more than $100,000.

“It’s been the most unbelievable stock I’ve ever owned," said Daut, a 63-year-old lawyer. “It’s probably the stock that one should never sell."

Daut is now planning to retire in the next year or so, instead of waiting until he is 67 as he had previously intended.

“Nvidia has allowed me to not worry about finances anymore," he said. “It’s really made my life pretty comfortable."

His regret? “I wish I had invested more than I did originally."

Nicki Bourlioufas, Sydney, Australia

Public-relations professional Nicki Bourlioufas was working on an assignment for a client when she learned about Nvidia. Through writing pitches for a financial firm that offered a videogame-related fund in which Nvidia was the largest holding, she became convinced that Nvidia could make a good investment.

She started buying Nvidia in her personal portfolio at the beginning of 2022, putting about $36,000 into the stock over the course of a few months. The position is now worth around $200,000. She may use some of those shares to help pay for a second home.

“I see them as gold," the 53-year-old said of her Nvidia shares.

Bourlioufas doesn’t think she’ll ever sell all of her Nvidia stock because she sees the company as such a dominant player in the AI market and broader need for computer processing power.

“With Nvidia, I do not see the shares falling over the long-term," she said.

Chris Kawaja, Ross, Calif.

When 48-year-old Chris Kawaja first used the AI chatbot ChatGPT at the end of 2022, he thought it was game-changing technology. Since he couldn’t invest in ChatGPT’s maker, OpenAI, he decided to ask the chatbot for stock ideas that could benefit from widespread use of AI. ChatGPT named Nvidia as the No. 1 stock.

He bought Nvidia shares for an average price of about $18, split adjusted. At the time, it made up more than a third of his stock portfolio.

Now, Nvidia’s popularity is making him nervous. He is worried Nvidia could become a stock like Qualcomm, which ballooned, then crashed, during the dot-com bubble.

“We’ve hit this point where everybody has to own the stock," said Kawaja, a real-estate developer.

He has been trimming his position, donating a portion to causes such as climate-change initiatives and Unicef. He has also moved some of his money into a semiconductor index. His Nvidia position is now worth around $800,000, and he plans to donate more to charity.

Still, investing in Nvidia has been “incredibly thrilling," Kawaja said. “I feel like we’re watching history unfold."

Jason Zweig and Asa Fitch contributed to this article.

Write to Hannah Miao at hannah.miao@wsj.com