Problem could be economical. The rich want to get richer and more powerful, the poor and rest of the 99% have issues. Solving a lot of these issues would mean less wealth and power for the rich. So they need to create scapegoats. And racist stereotypes are probably the easiest way to do that. Close second are the people who think differently than [your_group].

helps that the same rich people have lots of influence over what the rest sees, hears and thinks.

They say money is the root of all evil, and I think that is the core issue. It's unchecked greed and blind nationalism. Political and racial polarization is profitable. Selling guns and ammo is profitable. Being a corrupt politician who helps their rich friends make more money is profitable.

> there’s no evil army here locking people up.

Not what you meant, but that evil army is called ICE.