I'm not trying to argue that entrepreneurship isn't a great path to pursue for many people, but I disagree with the simplistic picture that people sometime paint wherein entrepreneurship is always glamorous and employment is always dreary.
Disclaimer: I work for Facebook.
It doesn't always always have to be about money. Open source software gives people to build something, break some new ground and make a change. I guess that's the same drive that gets people to found or be part of all kinds of efforts that extend beyond software and startups.
It's no coincidence that founders who get bought by BigCo's end up looking miserable 12 months down the line, after being demoted to an employee, who doesn't have full control of their baby any more.