Nobody — not William Julius Wilson, not Larry Mishel, not yours truly — denies that the bad effects of reduced opportunity would be much less if people always did what was in their best long-term interests. But people often don’t, which is why loss of economic opportunity can be socially as well as economically destructive. That’s not crude materialism, it’s saying that people are human.
I just want to point out PK's implicit denial that people are 1) utility enhancing agents, 2) forward thinking, and 3) perfectly rational.
Of course, people who do believe these things also claim Krugman is an idiot. Go figure.
That is all.