It might not have paid back the initial investment, but the company isn't bankrupt, and you've heard of it.

By the standards of people who invest in 100 start-ups at once, that's success.

You don't need to sell your stake for it to be a winner. It's a winner because his stake in the company is worth significantly more than when he bought it.

Plus the bragging rights: a lot of the angel and VC buzz seems to be about playing for status (versus playing for money).

You see this with celebrities investing, and with the intro "I was an early investor in ____" brag.