This has to do with the second cause. High housing costs in the most productive metro areas have turned places like Silicon Valley and Manhattan into playgrounds for plutocrats. Tighter land-use regulations in rich metros pushed up housing values, as the Harvard economists Peter Ganong and Daniel Shoag have written. That means that lower-income families, who would benefit from living near these bustling job centers, can’t afford to move there. As a result, rich young college graduates have clustered in a handful of cities while the rest of American movers are going to sunbelt suburbs with cheap housing. Moving toward affordability has replaced moving to opportunity.

Third, the growth of large companies has clearly sapped some of the dynamism from the U.S. economy. As I've reported, the decline in entrepreneurship has coincided with the rise of new monopolies—across retail, healthcare, and tech—that make it harder to start a new successful firm in these industries. Starting in the late 1970s, antitrust regulators stopped cracking down on large companies as long as they provided cheap products for consumers. Since 1978, the share of U.S. firms that are startups has fallen by 50 percent.

At an event this week at Politics & Prose, a bookstore in Washington, D.C., I asked Cowen whether he regarded Trump as the outcome of American complacency or as a kind of vaccine that would cure Americans of their indolence. He sided with the former, explaining that he had long thought that a constitutional crisis or a figure like Trump becoming president might happen in the distant future. He also said that in many ways, Trump is the perfect manifestation of a country that has lost interest in new ideas. “Make America Great Again” is an appeal to nostalgia, a promise to bring back the economics and culture of the 1950s, not to do anything new.

Cowen’s book performs the trick of all successful idea-driven non-fiction. It provides an open invitation for the reader to think deeply, even when deep thinking leads to some disagreement. At Politics & Prose, Cowen and I discussed a thesis common to his book and mine. Today’s algorithmic media, like Facebook, Pandora, and dating apps, specializes in offering users content that is “optimally new”—familiar, yet surprising. Cowen argues that these technologies wall off anything that is too novel, which feeds complacency. It’s a fair point. But dating apps also increase the supply of potentially discoverable partners, which leads to more dating. I wonder: Does waiting until your late 20s to settle down with a partner signal complacency, or the opposite?

Elite complacency is a complicated idea, too. Cowen is right that American elites have clearly sorted themselves into like-minded, high-income communities that pass rules against new housing construction, which isolates them from the rest of the country. But they are also restless strivers. Americans work longer hours than almost any similarly rich country in the world, and rich Americans work more than they did 30 years ago. As their leisure time has declined, affluent couples spend significantly more money on their children than they used to, providing for an expensive portfolio of tutoring, music lessons, and summer camps.