Rejecting all evidence, denying observations, and leaning heavily on half-baked hypothesis that culminate somehow on a gotcha. That sounds an awful lot like something someone who "does their own research" would say.
Yes, extreme levels of high-intensity exercise have adverse side effects. Cross-fit and rhadbo is an example.
https://en.wikipedia.org/wiki/Rhabdomyolysis
Drinking water also does everyone good, and everyone's health will improve if they increase their water intake, but drinking water in excess can also be fatal. Does this mean that the idea that drinking water does you good "does not make a priori sense"?
No, it doesn't.