It's really quite simple, contrary to the head-scratching perplexity of power establishment media mavens and politicos of the ruling two-party cartel.
The answer, is psychological.
Reactionaries have a persecution complex- even though they are a powerful, privileged group in most countries.
Trump's supporters, and those who gravitate towards him like iron filings attracted to a magnet, are reactionaries. A core part of the psychic makeups of reactionaries is a strong feeling of being unfairly victimized. Here are just a few of innumerable examples.
In the U.S., rightwing media is an unending stream of imaginary grievances that "conservatives" have. They present themselves as a persecuted, marginalized group. Given the dominance of reactionaries in America, this is delusional in the extreme.
Another example: the Nazis of Germany. "Aryans" were horribly victimized by Jews. This is why Jews had to be eliminated.
So by loudly presenting himself as a victim of unjust persecution, Trump plucks hard on this basic string within the reactionary psyche. That doesn't mean he doesn't really feel himself to be a victim. He has had such an extraordinarily privileged life, during which he has gotten away with virtually all of his misdeeds and crimes, that he probably really believes being finally, at long last, being called to account for something is persecution. Also he is a guilt-free, conscience-less narcissist. ( I'll tell you someone who thoroughly believed his own propaganda- Adolf Hitler. But he may have been more sincere than Trump.)
Trump instinctively plays directly to this psychological affinity with his "base," the deep-seated delusion that they are being victimized by gays, trans people, immigrants (just the "non-white" ones) and oh- whisper this one- Jews. And above all, by "Liberals" "the Left" "socialists" and even "communists." (Trump uses those terms.) Trump has repeatedly proclaimed to his mobs of supporters regarding his criminal indictments that "They're not just coming after me. They're coming after you." Thus does he reinforce the shared sense of victimhood with his "base."
Another thing that Trump's fans find appealing is his overt boorishness. It appeals to their anti-social nature. Ronald Dion DeSantis and the GOP generally also tap into that attitude with demonization of "wokeness," which refers to awareness of social injustice. That in turn is an evolution from the theme of gleefully attacking "political correctness," which is code for basic decency and consideration for the feelings of others who aren't straight white males and anti-feminist women.
So what accounts for the upsurge of support for Trump whenever there are legal attempts to call him to account for his crimes is his vociferous insistence that he is a victim of unjust persecution. That resonates deeply in reactionary psyches.
"How DARE you indict Me for My crimes!!"
All this is just a natural progression for the Republican Party, which has manifested all the nastiness, political savagery, take no prisoners attacks on Democrats, charges of "treason," posturing as the REAL Americans and more patriotic than thou, since at least the immediate aftermath of World War II. Go read up on the career of Richard Nixon, and you'll see what I mean. The totalitarian nature of the GOP (Gang Of Plunderers) is revealed by its attitude that their rivals, the Democrats, are illegitimate. They painted Democrats as "fellow travelers" of Bolshevism if not as treasonous agents of communism during the 1940s nd 1950s (Nixon branded his first political rival for office, Congresswoman Helen Gahagan Douglas, as "the pink lady".) Through Newt Gingrich's deligitimization of Democrats during the Clinton regime to Mitch McConnell's goal of making Obama's term in office a "failed presidency," it's just one more step to Trump proclaiming that Democrats stole the 2020 election.
Through all this, the Democrats either turned the other cheek or played defense. Meanwhile "the media," the corporate oligarchical propaganda system, studiously played dumb. Being "neutral" is what they pretend is objectivity. But ACTUAL objectivity means describing reality accurately.
Which is not something anyone should rely on propagandists to do.
