This is just me speaking from a contemporary point of view. Maybe part of the equation is a struggle to have a comfortable life and then seeing a limited sample of others who are better off whether through a combination of hard work and good luck, or see some people gaming the system with impunity. A lot of arguments I hear about those sympathetic to conservative talking points often have anecdotal experiences of seeing people abuse welfare or allegedly not pay taxes because they're undocumented workers.
"Why should I support those illegals when my tax dollars go to help them when they don't pay tax themselves?"
"I've seen people who can't speak English buy steak and lobster with food stamps."
This resentment can then grow from continuous exposure to biased media portraying some bad actors burning or looting in protests. At that point it doesn't matter what actually caused the protests, because they've generalized all those people to be thugs undeserving of being listened to. After that, minorities are seen as a nuisance that must be rid of at all costs. It doesn't matter if they're documented or not, they must be bad because the police are arresting and hurting them.
I don't have a good way to defuse their anger. They are right that some people in the minority act like criminals. They don't want to separate the good from the bad and just want to get rid of everyone whom the media and those in their echo chamber say are causing trouble.