I have not studied any science about whether natural selection would filter out predisposition to leeching. I presume nature will anneal to the resources available even if they’re a self-destructive power vacuum. Genetic evolution moves far too slowly anyway for that to make any sense. Although afair Freeman Dyson (when he obliterated Richard Dawkins) argued that cultural/technological change is a form of evolution which evolves much faster.

In any case, I agree we are entering a very dangerous potentially megadeath totalitarian juncture. We also have a Maunder Minimum coming and the changes to the climate and widespread natural disasters (e.g. drought/flooding) could potentially disrupt civilization. Technology may rescue us.