Once you reach a certain point money simply doesn't matter. They mentioned Groupon: Andrew Mason knew that whatever happened he was never going to have to worry about money again. When you have that luxury, you go with your heart, and it usually isn't with the money. Even after he was fired he made out like a bandit.

The same thing goes for a lot of these founders. When you get a substantial buyout offer, you've done something very few people have. Even if you blow it, odds are someone else will fund your next startup. Either way you probably won't have to worry about money. Once a startup is funded, the founder isn't rich but the company usually pays the bills so he can focus squarely on work.

I don't think we should reject the allure of money, it goes against human nature. But the ultimate motivation is freedom. That's what money gives you; freedom to do what you love. If what you love is building a startup the money becomes insignificant, but having enough to let you pursue your passion comfortably is very important.