A few years ago I was getting a ride home from a party with a guy in his early twenties. I lived in a gentrified neighborhood I could no longer pretend to afford, and he lived, it emerged, with his parents. “Good for you,” I said. “I think that’s great.” We hit a stoplight and he turned to look at me. “Do you?” he asked, with a sudden edge of cynicism in his voice. “Do you really?” I could hear what he was thinking: I guess you’re trying to be nice or whatever, but nobody thinks it’s “great” when a...