I think your chances of getting an enormous cashout are more or less independent of whether you work sixteen-hour days. If you have a great product that people want and the skills to implement it, what's the real difference if you work eighty hours a week instead of forty? Maybe you get the first version written in half (or more likely two thirds) of the time? Big deal.
Sure, there are probably some cases on the margin where speed really matters. But I think that if your product isn't going to take off then working a bit harder won't make it to do, and if your product is going to take off then you can probably get away with eight hour days anyway.