ERIC LEFKOFSKY

$2.8

BILLION  SELF-MADE SCORE: * SOURCE: GROUPON AGE: 50 RESIDENCE: GLENCOE, IL PHILANTHROPY SCORE: The Groupon cofounder’s latest startup, Tempus, is trying to use big data to improve cancer treatment. The company, founded in 2015, raised $200 million at a $3.1 billion valuation in May. Lefkofsky’s entrepreneurial journey began while he was a student at the University of Michigan, where he started a carpet business that he estimates generated hundreds of thousands of dollars in sales. He went on to found five companies, including Groupon and Tempus.