There's no indication that middle-income families feel resentful about the bigger mansions and yachts. But the near-rich, whose social circles intersect those of the rich, are subtly influenced by them.

Ever since the Great Depression, economists have known that demand shortages tend to persist in the wake of severe financial crises like the ones that happened in 1929 and 2008.

Prescriptive regulations, such as telling electric utilities what kinds of coal to burn or what kinds of scrubbers to install on their smokestacks, were not only intrusive, they were also grossly inefficient.

Every group spends more when its income grows.

The upshot is that to send its children to a school of even average quality, a family must outbid half of other similar families who are pursuing the same goal. And that's become dramatically more expensive because of the growth in median house size, which was in turn caused by higher spending at the top.

In the long run, greater investment would mean greater productivity and income growth.

There's no indication that middle-income families feel resentful about the bigger mansions and yachts. But the near-rich, whose social circles intersect those of the rich, are subtly influenced by them.