How similar are your ideas? Is there a chance that you could be an early employee at those companies? In order for it to be worth your time, you have to have a chance of success, and you know that the other team already has an advantage of money. If you don't think you can make it, get in touch with them and see how you can help.

You know how the saying goes: "If you can't beat 'em, join 'em."