France's Lois Boisson entered the French Open ranked No. 361 with just $148,000 in career earnings. After shocking world No. 3 Jessica Pegula, she's guaranteed over $500,000—and a chance to multiply that even further.

LEGO was part of Kristiansen's life from the time he was born in 1947. He is credited as having been an inspiration for many of LEGO's early products, and even worked as a tester of both play sets and their instructions as a child.

Tim Sweeney created the global phenomenon Fortnite and gave it away for free. That turned out to be a brilliant strategy that has made him a billionaire.