I wonder how many projects never get completed because of lack of enthusiasm / jaded effect?
Almost all of them. That's the biggest problem with anything more than the simplest of games ... maintaining drive and enthusiasm. Even if you love the game you're making, it's tough to keep up your momentum as the months drag on.
I'd like to offer a solution, but I don't really have one. I will say though that it boils down to project management and having the ability to say "no". Keep the scope of the project reigned in and don't keep adding things on the fly. If you don't have a defined goal, you'll never reach it.
It comes down to the ability to ship. Lots of people can write games. Of those people, only a fraction have what it takes to actually ship/release.