Why would playing high frame rate games alter your vision? Is your brain reprogrammed when viewing image transitions at frame rates so high that they cant even be noticed.

Further research needed probably. But it doesn't seem to be far fetched to guess that what you do influences how you work.

I think you can notice high frame rates. Difference between 60 and 120 fps is striking. Even between 90 and 120. And everyone I was showing my phone that does 60, 90 or 120Hz could see it.

Conversely I don't see much difference between 120 and 240 fps.

Because it provides a different perspective, figuratively. I think that might also be a reason why HFR movies feel weird for some people, it's very much a comfort zone.