First off, 3D games existed before NVIDIA. NVIDIA wasn't even first to market for making dedicated 3D acceleration hardware.
CUDA existed before Bitcoin and was used for physics and chemistry simulations when it first came out.
> "Compute that does nothing important"
Entertainment is important, so to just toss 3D games aside is asinine. I'll agree that crypto-mining is completely worthless. As far AI, certainly there's a lot of hype around it right now, and we're probably gonna see a lot of AI startups go belly-up in the next couple years, but it's definitely not a fad and isn't going away.
Being highly dismissive doesn't make you cool or edgy, just so you know.
Beyond that, there was no crystal ball, rather a useful physical product and software tools to make it accessible beyond a highly specialized set of users (I am not saying CUDA or anything is that accessible, but it makes GPU's useful to more than just game devs).