By 24, he was the founding president of Facebook, a tiny startup that would go on to become the biggest social network in the world. 

The 41-year-old, whose net worth is estimated to be about $2.7 billion, hasn't slowed a bit: he donates millions to philanthropic causes — and political ones — and lives an expensive lifestyle. 

Here's how Parker got his start, ended up at Facebook, and became a billionaire. 

Madeline Stone contributed to an earlier version of this story.