Greed is good, let us look at lions. A group of lionesses capture a prey, The male lion comes and eat his full, while the lionesses are obliged to wait until he is done.
The group of lionesses could easily unite and chase him away. If they did that, they would starve him to death. There would be no male to breed them and soon lions would cease to exist.
No matter how greedy the lion is he can only eat a bellyfull and go to sleep. The whole family will thrive.