In small groups, where cooperation was the iterated prisoners' dilemma, it was quite rational to act irrationally, declining unequal sharing for example. See the allocate / veto game, where disgust at "unfairness" makes one side turn down free money.
Those instincts run deep. They drive the politics of envy and tribal resentment.
But to prosper we must embrace rational economics, and learn to live with unequally-rich, as superior to equally poor.