Yeah, storage prices also suck :-(

I have misread the meaning of only in your sentence. Only for gaming and nothing else, almost 0%.

How many people realistically only uses their desktop PC for gaming […].

The majority? Not everyone can or wants to afford 10 gaming gadgets just to play the same games on different devices.

what’s the benefit of using a “gaming” distro

There are some benefits. (I haven’t and don’t plan on watching the video, so I don’t know which they used.) CachyOS has some optimized kernels that help squeeze out more performance out of latency sensitive games. It is not earth-shattering, but there are measurable differences. One personal example was CS2. It ran fine on Fedora 42, but on Cachy there was noticeable less stutter when there was a lot of action.

.ml is hard at it