I was designing Mac graphics accelerators in the early 90s, one thing I learned is that perceived performance follows a sort of S curve, there's an area where everything is terribly slow and any change is good but it's slow, then you hit the curve every performance increase is obvious, wonderful, makes new stuff possible - that's where you start selling big if you're leading the pack, then you hit an area where performance is "good enough", double the performance and the perceived increase is far less - now you're fighting for "cheapest", not so good for your company.
That was for 2D, bigger faster 3D enables new sorts of games so that market has been growing for far longer.