National Defense

[Martin Hash]

1) All morals aside, another tribe is simply a resource to be exploited. If conquest costs more than the loot then "peace," but when the equation reverses, attack.
2) Normally, armed people in the other tribe provide the deterrence to attack. In an egalitarian society, those armed people fight for themselves first, but understand that their potential death also helps others keep their stuff. In a disastrously unequal society, the people willing to die to keep their shack while maintaining the lifestyle of the super-wealthy goes down significantly.
3) Economics says that there needs to be enough balance, even if greatly weighted to one side, that the vast majority will be willing to die for the small minority.