I think the answer is surprisingly few. This makes it hard because you need to have the ganas enough to a) quit b) devote most of your time. On top of that, you

I think the answer is surprisingly few. This makes it hard because you need to have the ganas enough to a) quit b) devote most of your time. On top of that, you need to have a co-founder who is willing to make the same sacrifice. Having a co-founder who isn't on the same page isn't completely worthless but it can be terribly frustrating.