Writers know that getting the first draft out the door is a good start to the story. They’ll also expect that that first draft will be subject to a massacre of editing – this is the nature of writing a book. But If they didn’t get past that first draft – the draft full of total crap – they wouldn’t be able to find the improvements of the next draft.
That first business idea will probably be stupid. But once it is in the market, it is subject to the feedback of the marketplace, and if persistence plays its part, it will be subject to the iterative forces that marketplace provides.
So, quite simply, if you think you have a stupid idea, test it out. Find out what part of it is least stupid, and grow it from there. Once you get past the crap ideas, a fresh, genius idea just might appear. Keep searching.