His appeal is the same as Bernie's was. While most oligarchy controlled politicians refuse to recognize how shitty things are, Bernie and Trump got up and said what everyone who lives in the real world knows to be true: shit's fucked up. The difference was that Bernie recognized it's the oligarchy (including Trump, even though he's kinda his own oligarchy) that's fucking things up, while Trump just let the racists and misogynists and bigots choose whoever they wanted to blame and agreed with them. After all, he couldn't point the finger at himself (probably literally, since he's a narcissist his brain won't let him).

Basically he recognizes that their lives are shit, and gives them license to openly blame whoever they want to blame. Thanks to decades of Republican bullshit, they tend to want to blame anyone who's not a white Christian.