In decades past, primarily white Americans in rust-belt/southern states have relied on well-paying factory jobs in industry: mining, steel working, automobile manufacturing, etc. Graduate from college, get married, get a union job in the local factory and have a good life.
Globalization has largely ended this. And there's been little in the way of government assistance from either party trying to improve the lot of such folk.
Always mistrustful of government and now hurting economically, a lot of Americans are pissed off and just want major change.
Into the mix is the godawful distribution of wealth - a fraction of the populace holds the majority of wealth. Of itself, this is alone is enough to spark massive unrest.
Which is to say, the MAGA folk are by-in-large not well off economically, mistrustful of government, undereducated, religious, and, above all, want change. They're ripe for demagoguery. And Trump delivers a message they want to believe in.
It's a mess - and will take decades to address.