Peter Thiel: $3 Billion
Peter Thiel, cofounder of PayPal, was Facebook's first investor in 2004 when he invested $500,000 in the fledgling social network. Since that investment, Thiel has made early-stage investments in many startups including LinkedIn, Yammer and Yelp.
Today his 3 percent stake in Facebook could earn him $3 billion—that's more than a quadriggigillion times return on the investment. Now that was a good business decision.