If you want to know why fascism is ascendant in the US, it's because almost everyone in proximity to power has been nudging it along, often for selfish reasons, and sometimes for no reason at all other than someone annoyed them.
The biggest driver, of course, is white supremacy, mainly because that's who the rich and powerful in this country have always been. The original sin of this country, slavery, and its legacy, which no one in power has seriously tried to upend since the failure of Reconstruction.
American fascism has deep roots but the modern wave is based in a multi-pronged reaction against fairly recent events: Obama and the perceived institutional failure to keep power in white hands; COVID and pandemic precautions, borne of eugenics but also a petty, aggrieved sense of entitlement; tech bros and investment capital going to war with workers and unions over very modest gains, and women and queer people's challenge to patriarchal authority, which the right embodied in trans people.

The primary fascist figures each embrace aspects of this.

Trump, the rapist con man billionaire, destroying the government to enrich himself and keep himself out of jail.

Musk, the petty but incompetent CEO tyrant, who hates workers almost as much as his trans daughter.

RFK, Jr., the anti-vax steroid addict with worms in his brain, who oozes eugenics and wealthy entitlement from his pores.

But this picture wouldn't be complete without collaborators and fellow travelers from the Democratic Party.

Like Joe Biden, whose blood thirst for killing Palestinians outweighed any political sense. Or Eric Adams, the personification of the cop-as-Democrat, who still stands out as one of the most corrupt politicians of our era.

Not to mention a whole parade of useless, spineless, greedy, cowardly, racist, and otherwise bigoted Democrats, personified by that old skull, James Carville.

There's Jeff Bezos, of course, hijacking the Washington Post to be a mouthpiece for his own right-wing corporatist views. Or Mark Zuckerberg, whose Facebook has already been an enabler of genocide. But Tim Cook of Apple is just as happy to scrape and serve at the feet of Trump as anyone else at that level of power.
Almost everyone at the upper echelons of power, for decades, passed on the chance to prevent this from happening and in many cases accelerated it, gutting the tax and regulatory systems in place against it, merely because it was easier, it made them a buck, it didn't upset the donors or white voters, it helped them keep their seat for the nth time, or even just because it worked out a grudge against progressives.

@gwynnion It is pretty similar in other respects too, to Italy, Spain & Germany of the 1930’s.

A fear of the left drives the wealthy class to let the far right in. A far right which skillfully strides both a critique of the rich for the petit bourgeois class and a critique of socialism for the rich.