Almost as predictably as the sun rises in the East and sets in the West, the rich grow richer. “Wealth concentration in a few hands is the single most enduring economic pattern across all polities from Mesopotamia to the present—rarely interrupted, and then only for brief intervals,” the political scientist Jeffrey Winters, who studies oligarchies (including the United States) at Northwestern University, wrote in a 2017 paper. Maintaining dynastic fortunes once required physical might, Winters explained.