IMO your only real options are to (a) quit to do the other thing or (b) not quit and forget about the other thing. If you're funded, you can't do both. But the

IMO your only real options are to (a) quit to do the other thing or (b) not quit and forget about the other thing. If you're funded, you can't do both. But there's some nuance in how one can quit, which depends largely on how far along your current business is. If you have multiple cofounders and a solid team in place, you can just leave yourself. You talk to the investors first, and give them some sort of perk, such as a right of first refusal, or even spin it out of the current company (which means they get a small equity stake since your current company owns some of the new one). This is all fine, but only works if your current business is strong enough to run completely without you. If the current business isn't to that point yet, then leaving it will kill it, and dividing your attention is as good as leaving it. Not fair to the investors, not fair to the employees. So you sort of just grin and bear it. That's the hidden cost of taking funding and asking people (both investors and employees) to believe in you. But such is life.