I don’t even know what your point is anymore. Whatever it is, there are real examples (let’s stick with MRSA) of bacteria that are resistant that do very well from a fitness standpoint and are not going anywhere or losing that resistance. And this acquisition of resistance (or broad spread of an already existing resistant strain) is driven by the selective pressure of being in an antibiotic rich environment.

And here I am talking about the antibiotics that humans use, because the multitudes of naturally occurring molecules made by other bacteria, etc are not molecules we use clinically (other than the one or two that we’ve taken unchanged), so it does not matter if bacteria gain or lose resistance to them.