There's a counterpart to the 1% fallacy that Derek Sivers wrote about. (If you haven't read that, you should! It comes up in many contexts.) This counterpart, which could be considered the inductive case relative to the original, is the idea that you can grow any existing customer- or user-base. For example, "if I have a website that gets x visitors per day, surely I can get that to 1.5x".
It's a tempting thought, and one I found myself suspectible to. You know, with a little hustle, why couldn't you grow anything? I think the structural answer is that in theory you could, but turning Traf-O-Data into a billion dollar company might be inordinately harder than starting over with Microsoft. Everything eventually reaches a local maximum. Escaping it takes energy — possibly more than you can bring to bear on the problem.
This line of thinking validates traditional, top-down analysis. There's still a place for intuition — the future is mysterious, and not all markets are measurable — but it, too, can be honed. I threw my Chrome history into Alexa's traffic estimator and bucketed the results by order-of-magnitude. When I'm thinking about a web project, I can now mentally compare it to those on the list, and at least let my intuition speak more precisely.