It was a precondition to leaving Facebook that I wasn't going to start something that was just about chasing money.

Facebook was founded on February 4, 2004. On February 5, we were feeling pretty confident, even from observing the first few hours of usage. Students used it like crazy. They'd sign up then spend the next 3-4 hours on it. Then we'd go to lecture hall and see it on every computer screen there.

There are a lot of people building small ideas now. There's an idealization of being an entrepreneur, but the most important thing is to have a really great idea.