Matt Yglesias should give it a rest because he is adding to the confusion around issues of race and class, and because what we need is a clear discussion of class issues and how they play out in the USA. Short version: It’s Complicated. Yglesias is not contributing clear information. Time to stand down.
People do vote against their economic interests, and my guess is that they do so because they have overwhelmingly more important values — opposition to abortion or gay rights, for instance — or biases like racism, or that they believe that their economic insecurity is actually the fault of blacks or immigrants or other people Trump has targeted. Hillary Clinton’s proposed policies do not appeal to them because 1) as a point of pride they would not accept “welfare” or “a handout” under any circumstances, or 2) because their perception is that they never get anything from the social programs, which have such stringent means tests that only people living at poverty level actually benefit. This is often true, and for people moving out of poverty, it is often a very steep “sliding scale.”