Claim to fame: LinkedIn co-founder, Peter Griffin lookalike, champion of the world
Rough start: As a student, Reid Hoffman said he wanted to make an "impact" on the world, possibly through academia. Normally, this type of talk is a less-embarrassing way of saying "I'll probably be poor for a long, long time."
That's not quite what happened. Hoffman is currently a billionaire, with a net worth so high, a '60s Bond villain would demand it as ransom in exchange for not nuking the world. It took some time to get there, though. He had a job at Apple for a while, before starting SocialNet, which was essentially an early Friendster, which essentially means no one ever heard of it. He then moved on to a job at PayPal, where he learned the hard lessons of entrepreneurship. The experience paid off, though, earning him $1.5 billion by 2002, when he began work on LinkedIn, which has now earned him about $4.6 billion. And he didn't start getting anywhere until after his 30th birthday.