Probably because that demographic is always so under-boot all the time.
In the grand scheme of things, I wouldn't really characterize them as 'oppressed'. It's just that the trends in the world economy have screwed their lives up, and they haven't been properly retooled. The solution isn't to try and turn back the tide and force industry back into the US, and that won't happen either.
The one thing I just can't understand is how a bunch of middle-class, working-class white people, all pissed off about the political and social elite, saw a billionaire businessman and said, "Yeah, this is the guy that gets us."