The notion that “we don't adapt”, though, is really a euphemism for “people, who otherwise might not, are surviving to reproduce and are therefore not selected out”. But the truth is that death is still inevitable and people are still being selected out, and we are still, therefore adapting. The only thing that has changed is what environment we are being selected for: Earth in the Anthropocene.

The technology-caused changes of environment are so recent that we wouldn't have had adapted to them no matter what. Adaptation takes a long time, the last significant adaptation we've had is lactose tolerance (lactase persistence mutation) which was unusually fast to spread and took only a few thousand years to do so. A few centuries is so small time (for human generations - it's different for bacteria or insects) that we should expect literally zero adaptation even if the "pressure to improve" would be the same.

We're altering the environment rapidly. Environment has a large influence on gene expression. Not a biologist but that is more likely the reason.

There is absolutely no reason to think psychopaths were excluded from society. Chances are, they were very successful and run even more unchecked then now.