Instead, support for Trump correlates with racial resentment, which, in turn, I believe, often correlates with living in all-white communities where one doesn't actually meet or get to know African-Americans or non-white immigrants..
It's widely recognized that Trumpism also reflects people's living in a bubble where the only media or other information sources that they get to see are those confirming their ideological biases. Needless to say, this phenomenon is not limited to Trump supporters, and it's always unhealthy even if not always this toxic.
In this regard, however, I thought of two things that might usefully be put together. First, a shout-out to Cass Sunstein, who wrote about the self-selected media bubble phenomenon as early as 2002 in his book Republic.com (the revised or "2.0" edition of which is available here).
Second, I thought of something I heard about many years ago, when the post-Yugoslavian civil war between Serbs and Croats was at its height. I heard it said (via someone who grew up in Yugoslavia during the Tito era) that, for many years, intense Serb versus Croat ethnic identification was very much on the wane, at least in areas where members of both groups lived. It really seemed to be something from the past. There was intermarriage, people didn't strongly identify with their groups or stay away from the other one, etcetera. But then, of course, when the larger state broke up, ambitious Serb and Croat politicians deliberately took the opportunity to stir up ethnic hatred and violence as a way of strengthening their own political positions.
The fact that this proved so successful showed that people still remembered enough of those old hatreds to be capable of sinking back into them. The haters on both sides are fully morally responsible for what they became. But it was also an act of insidious political entrepreneurship by the leaders who chose to stir up the hatred, because they saw that it would be to their advantage.
I think there is something similar going on with Trumpism. Media entrepreneurs, from Fox News to the further-out fringes, have seen that they could build their audiences by exciting racial and ethnic hatred. Their consumers evidently decided to embrace this, but also were probably changed by exposure to it. So one can see this in part as a John Kenneth Galbraith-type manipulative advertising story, in which the entrepreneurs take an active role in shaping people's preferences, albeit requiring those people willingly to take the first, second, and third steps themselves.
This is a point that one could add to Sunstein's Republic.com analysis. Not only do people retreat into like-minded media bubbles, thus entirely separating their realities from each others' realities, but there's an entrepreneurial environment in which extremism and hatred "sell." Thus, powerful market incentives invite creating the sort of monstrous dysfunctionality that we see rampant in the 2016 presidential campaign.
I have no particular proposal to make about all this, but it might help one better to understand Trumpism, and in particular the nihilistic rage and hatred that seems to have consumed people who often aren't doing all that terribly.