I'd suspect it's reaction to large cultural shifts in the last couple of decades - including gay and trans rights, George Floyd and increased racial integration in media, me too, etc. For whatever reason, perhaps loss aversion, many people tend to react angrily and violently to change and the threat of change. Perhaps it's analogous to how communist movements in the early 20th century led to fascist movements a decade or two later.

I also don't think it's the US only, so you can't put it all on Trump. I'd argue Trump and similar figures around the world are the result of the above counter-reaction.

Radicals radicalize radicals.

Only stable conditions, equaliberiam or entropy deradicalize.

Social was a flash point. Large parts of society interacted for the first time. Echo chambers formed, energy level increase, radical leave the bubbles and new groups militerize in defense.

It made less sense to people out of the loop though. Nazis, antifa, police are raciest, lgbtq, Christian nationalism, socialism, etc. All of these ideas were subcultures that grew bubble online cause they could (much like the Arab spring), and the radicals that formed and took action made big moves from everyone else's ignorance.

The majority didn't have the means, and frankly still don't, to hold the concepts or ideas as unique groups so instead they mapped onto the two party system warts and all. Because "right wing" was Republican the opposing side told everyone "right wing" is Republican. So Republican had to either disavow or defend them, but when these groups wanted to act politically they had almost no choice but to fit in predefined parties.

Its been mostly good, that's the crazy thing, gay rights, trans rights, police reforms, the DoJ has how many anti trust cases going on now?, how unions are forming?, etc

I’m pretty sure that would be ex uno, plura

why? because it's all they have left.

demographics are changing. their population is aging. their kids hate the way they live and move away.