Serena Williams is now the first athlete ever to hit Forbes’ annual list of America’s Richest Self-Made Women, with an estimated fortune of $225 million, the vast majority of it having come via her brain and brand rather than her backhand. And over the past five years, she’s been quietly dropping money into 34 startups. In April, Williams formally announced that Serena Ventures is open for business, to fund others and launch companies herself.