Before the invention of agriculture it is almost surely not good to be the king. You can use your status to pick the best of things, but the amount of things you have is limited to what you can personally carry. And if your exactions become too onerous the people can simply leave for the hills. But once a population becomes agricultural, people cannot leave for the hills. Hunting and gathering in the hills cannot support the population densities of agriculture in the irrigated plains, so departure means death for overwhelming numbers and also the loss of all of the value of the labor that has gone into ploughing and sowing and weeding. Agriculture opens a new career path: that of a specialist in systematic violence directed against other humans who makes threats to induce them to give you a third of their crop—or else.
A parasitic caste or class existing by virtue of their organized ability to take a substantial share of the agricultural (and craftwork) producers’ crops becomes the rule soon after the coming of agriculture. Such castes and classes live better albeit more dangerously than the peasants. (If they didn’t live better, after all, why accept the extra danger?)
Interesting throughout, you won’t read these paragraphs (only two of 17 are abstracted here) anywhere else as he’s just cut them from his book.