This may explain the phenomenon but it certainly doesn’t excuse it - just because something is natural doesn’t mean it’s smart or morally correct

This is not correct. First, in crisis situations people tend to cooperate more, even though naive model predicts that people would act in self-interest. Second, there have been cases of countries that collectively decided not to be poor, and they stopped being poor once external pressure has been removed. Case in point is a huge part of Eastern Europe after the fall of communism.