Serena Williams has been a professional tennis player since she was 14. Over the course of her nearly career, she's earned over $92.54 million in prize money, according to the Women's Tennis Association (WTA).
"I don't spend money — when I do it's on my daughter," Williams, 38, told People. Williams has a 2-year-old daughter, Alexis Olympia Ohanian Jr., with Reddit co-founder Alexis Ohanian.
In 2019, Williams was the only woman athlete to make Forbes' list of the world's highest-paid athletes. Last year, she made $4.3 million in prize money, according to the WTA. Another $25 million came from endorsements from sponsors such as Nike, J.P. Morgan and Gatorade, Forbes reported.
So what does one of the greatest athletes of all time do with her hard-earned money?
"I usually invest my funds. I am the most boring spender ever," Williams told People. "Don't spend it, invest it."
(Finance experts from Kevin O'leary to Suze Orman to Tom Corley agree with that advice. Investing your money is the way to wealth, "thanks to the magic of compounding," according to Jim Cramer, host of CNBC's "Mad Money.")
Williams has always been a saver: When she earned her first million, she took it directly to the bank, she said in a 2017 interview with Uninterrupted. Often she would forget to collect her earnings after winning tennis tournaments, she said.
"I never, never picked it up, so at the end of the year, the tournament directors would literally hand me the check because I would never go get it," she said in the 2017 interview.
Even today, Williams is "really bad at treating myself," she told People. "I am learning how to treat myself more. I am working on it. I've thought about some jewelry," she says.
Williams has 23 Grand Slam titles under her belt and is currently ranked the No. 10 women's tennis player in the world. She's the fourth woman ever to be ranked in the WTA top 10 after turning 38.
In addition to tennis, Williams has her own direct-to-consumer fashion line, called S by Serena, and runs a venture capital firm, Serena Ventures, which has invested in more than 30 startups since 2014.
The firm focuses on new companies that are founded by women or minorities, and its mission is "to be more inclusive," Williams told CNBC in September. For example, Serena Ventures has invested in Billie, The Wing, Lola and Daily Harvest.
"When you think of Silicon Valley, you think of a lot of investments, you think it's so exclusive, like 'how do I get in that' and 'I can't invest cause I don't know and there's no way in,'" Williams told CNBC. "But we want to make a way where it has more inclusivity and more impact."
Still, Williams doesn't like to "gamble" when it comes to investing, she told Forbes in June. "I'm the most non-taking-a-chance kind of a person, but I felt like seed was where we wanted to be."
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Correction: The story has been revised to reflect the Women's Tennis Association's correct name.