Some people are great at coming up with new ideas but quickly bore with the implementation. Some people can relentlessly improve on an existing thing but can't come up with the initial idea. Some people are great stewards of an established program but don't thrive in the chaos of rapid iteration.
I think instead of trying to mold yourself into something you're not naturally good at, you should try to figure out what you are naturally good at and build a team around it to support you.
I'm speaking in broad strokes of course, but reading your post, I think you are just not going to be a sole proprietor. You need a team member who can catch your early enthusiasm and then help see the project through to completion.
You need a finisher. Not every starter is a finisher, and not every finisher is a starter, and not every finisher is a good maintainer, either. They're different things.