The thing I always remind folks of in that situation is that to succeed at many things, particularly creative things like YouTube and writing, you have to do it for intrinsic reasons. You want the writing or videos out there because somehow the act of putting them together and publishing satisfies you even if not another single person was there to see it.
I think it applies really well in entrepreneurship. It's not a strict rule obviously. There's people making stuff for other people all the time. But one of the best ways to stick through the ups and downs of entrepreneurship is to be working on something that has that intrinsic satisfaction. You're the best user. Even if no one buys the thing, at least you have a piece of kit that fixes some need you have.