#6:. Sergey Brin | Co-founder of Google, Inc. | Net worth: $32.8 Billion USD

Google co-founder Sergey Brin has never been richer. The company’s stock surged to an all-time high in July 2015 after new Chief Financial Officer Ruth Porat promised to rein in expenses and after the company reported growth in mobile search and strength at YouTube. For his part, Brin has been trying to convince shareholders that spending on moonshots is worth it.

In a June 2015 letter filed with the SEC prior to Google’s annual shareholder meeting, Brin defended the ambitious, uncertain projects that his Google X division oversees. Besides the ill-fated Google Glass, the projects include self-driving cars, which hit public roads for the first time last summer, and contact lenses that can monitor glucose levels in people with diabetes.

In May 2015, Brin quietly finalized his divorce with Anne Wojcicki, CEO of genetic testing firm 23andMe, nearly two years after his affair with a young Google manager made headlines. The son of two academics, Brin emigrated to the U.S. from Moscow when he was six. He founded Google with Larry Page in 1998, when they were both computer science Ph.D. students at Stanford University.