I don’t know if this going to help you, but after enough introspection in all my failures, the one reason that always comes up is ignorance. And I think many people would say the same thing.

So my advice would be to do more research. Then more research about your research. And keep going like your life depends on it.

Maybe doubting your ideas is a good thing. You’re been realistically skeptical.

Somewhere, there’s an expert who can tell you, with confidence, if your idea is good or bad, and how to improve it. So go ahead and find that person or become that person.