This answer can be found in Chapter 14 of Guns, Germs, and Steel. According to Diamond, political elites can gain support for their rule, which involves the expropriation of wealth from common people, through one of four means:
- They can arm elites, which will obviously make repression of common people easier.
- They can redistribute wealth in "popular ways," which will make the common people happy.
- They can use their "monopoly of force to promote happiness," usually by creating peace and order, which are so desirable that people are usually willing to exchange freedom for them.
- They can create an "ideology or religion" justifying kleptocracy, or taking wealth from the people. Of all the methods, this perhaps has the most desirable residual effects, because it also helps persuade people to get along with each other.
Source: Diamond, Guns, Germs, and Steel, 277-278.