[CamperBob2]

A decline in cooperation is probably a natural consequence of prosperity. Groups with more prosperous, empowered individuals see a decline in mutual cooperation over time, simply because it's not as necessary for their members to stick together.

Meanwhile, groups with fewer prosperous members tend toward the opposite behavior. They realize that the only way to compete with the "in group" is to gang up on them... or at least, that's what they tell themselves.

It hardly seems necessary to point to US electoral politics as a case in point.