We had psychiatrists claiming it was mass hysteria until fairly recently.

Honestly i’m still not sure, but what if it is? Is there any proof that it is not?

I think that there’s never been found any physically measurable indication for ME/CFS or Long Covid. From all we know, either it’s hormone-meditated and we have no fucking clue what hormone(s) do(es) it, or it is really psychological, maybe some mechanism buried deep within the subconscious.