Peter Thiel

In the summer of 2004, Peter Thiel wrote a $500,000 check for a 10.2% stake in a college social network run by a 19-year-old Harvard dropout named Mark Zuckerberg. It was Facebook's first outside investment and valued the company at roughly $5 million. At the time, Facebook was available only at Harvard and a handful of other universities. Most investors saw it as a niche project — Friendster and MySpace were the dominant social networks, and the space seemed crowded and faddish.

Thiel saw something different. Drawing on his deep thinking about monopoly dynamics (later articulated in his book "Zero to One"), he recognized that Facebook's real-name identity system and network effects could create an insurmountable competitive moat. He understood that the social graph — the map of real-world relationships — was the most valuable dataset in the history of the internet. When Facebook went public in 2012, Thiel sold most of his shares for over $1 billion. That $500,000 angel check generated a 2,000x return and remains one of the greatest venture investments ever made.