From 1981 to 1983, he calculated, buybacks consumed only 4 percent of net income for the largest U.S. companies. By 1996, it was 27 percent; by 2006, 46 percent; and by 2016, 50 percent. Two generations later, in any prosperous American city, the unequal effects are plain—Teslas, luxury high-rises, avocado toast. And tents.