OK, I hope my question doesn’t get misunderstood, I can see how that could happen.
Just a product of overthinking.
Idea is that we can live fairly easily even with some diseases/disorders which could be-life threatening. Many of these are hereditary.
Since modern medicine increases our survival capabilities, the “weaker” individuals can also survive and have offsprings that could potentially inherit these weaknesses, and as this continues it could perhaps leave nearly all people suffering from such conditions further into future.
Does that sound like a realistic scenario? (Assuming we don’t destroy ourselves along with the environment first…)
Plenty of answers already.
I’d like to point out that it’s not medicine alone, but empathy that changes natural selection. We have evidence of our ancestors caring for members of their tribe that would have been unable to survive otherwise.
But while in some edge cases (some diseases) you could make an argument that it’s bad for future humanity for some reason, it’s overall good, because it enables a larger population. And a larger population has a better chance of mutating to fit changing environments. Or to phrase it differently: diversification comes first, selection can wait.