Holy strawman batman
Mutherfucker pulled that straight out of his ass.
Nationalism is about face.. Always has been. When a minority rises in status compared to you, your place in society diminishes. If prosperity does not hit all groups equally, the less-prosperous experience a prestige hit compared to the more prosperous. They can still be better off - If your immigrant neighbor goes from zero cars to one, you experience a real loss of face if you don't go from one car to two. You used to be superior. Now you're equal. That doesn't mean the immigrants are now as prestigious as you, that means that you are losing the rat race.
This is why liberalism has always been about erasing ethnic and social boundaries and replacing them with civil constructs. "My fellow Americans" is inclusive; "the South will rise again" is not. If you don't want ethnicity and class to blow up in your face like a hidden Claymore you need to build an identity greater than "Hill people."
This dumb fuck right here? "I'm Hill People. We're proud and don't you dare denigrate us. Now watch as I spend 300 pages denigrating us." What grand project does he believe in? Peter Fucking Thiel.
Trump happened because large swaths of the country no longer believe in the American project. So they fell back on tribalism. And here we are.