[b_t_s]

Walk away. If you want to be a good guy, walk away and do something else. Besides, it sounds like the idea has zero validation. That means your gut feeling that you can connect with significant numbers of customers who want this thing and are willing to pay you meaningful sums of money for it has a pretty high chance of being completely wrong.

As far as having 4 idea guys as cofounders, that's my personal vision of hell. I've been in that situation with one designer and one idea guy just doing a couple of iphone apps on the side for fun. It quickly turned into general unpleasantness all round as our idea guy, having nothing useful to do, busied himself with being Chef Executive A$@hat. You've got 4 of them? shudder I'd probably turn that down even they had funding and paying customers.