As a writer, I've got used to some great ideas turning into rather shitty work. It happens. It is part of the game. The scary part is when that idea has been with you for years and over time has grown in value. It has become less an object but rather a companion. Something you believe can transform into something wonderful. But what if through my own shoddy work that I mangle and mutate it, and it doesn't become what I have in my mind. The finished story is never ever going to be as great or magical as the idea that inspired the work, but what if my own tools are what makes it an abomination that could have been pristine. The even scarier part is what if that idea is the best that I'll ever have and I'm just stuck trying to hammer off the deformities and try to make it some battered version of my dreams.
But you never know any of that until you start digging. I think it is about time.