Edited for formatting
First, his personal background. Trump was born into relative wealth, and spent much of his professional career and personal life mingling with, and making connections within, the group of people that we would consider the "Ruling Class". Establishment politicians, lobbyists, billionaires, celebrities, so on and so forth. His longtime former friendship with the Clintons (and possibly with Epstein) is well known so I won't go into that here.
Next, his actions- despite being a member of the "ruling class" by most metrics, he apparently chose to throw it all away- the connections, the social credibility, so he could claim to be a champion of the Working Class Americans. People tend to interpret this as evidence of Trump's genuineness, that he genuinely cared and believed in what he was saying. However, in light of his behavior while in office, I doubt this.
His administration- he was elected in 2016, and until 2018 he and the GOP had control of Congress and the White House. Despite this, he pushed almost no real congressional domestic policy during this time. Most of his legislation was passed thru executive orders that can be easily reversed (many were struck down by judges, others are being reversed by Biden). Border wall, natch. Mass deportation, natch (Obama deported more, ffs). Limited tax cuts that expire in a few years. Banned bump stocks, a longtime gun-control goal as well.
His only real accomplishments were in the Foreign policy arena, with not starting wars, and the trade talks with China and Korea, and it remains to be seen how effective those will be long-term, with Biden working against both.
Perhaps most telling- he claimed that the GOP lost the 2016 popular vote because of voter fraud- then did nothing to rectify this, again despite having control of Congress.
So to summarize, he had a handful of minor accomplishments that were mostly enacted thru easily reversed means, and did not meaningfully solve any of the issues that his party campaigned on despite having two years to do so. And despite pointing out flaws in the voting system that were hurting his party, he did nothing.
Second half of his term- he changes strategy, ditching the nationalist "send em all back" rhetoric in favor of "Democrats are the real racists". We saw how this played out in 2020 election with Trump gaining in every demographic except his core base of white men and women, that he more or less put on the back burner.
So after failing to meaningfully enact any of his 2016 campaign promises, deliberately pushing his original base to the back of the bus, and leaving the door wide open to potential fraud- he loses under suspicious circumstances that almost certainly relate to voter fraud. He hires terrible lawyers that focus on irrelevant aspects of cases while ignoring the important parts, that can't properly file cases or present them in court, and so on. Then the spectacle at the Capitol which the media spun as terrorism.
Then there is Qanon. Trump's refusal to condemn or disavow Qanon despite it being at best false and at worst deliberately misleading, seems in hindsight to have been deliberate. And what was the end result of Qanon? Wait two more weeks, "trust the plan" and don't do anything to fight back.
To Conclude Trump ran on a genuinely right wing nationalist platform, failed to enact almost all of it despite having the ability to do so, switched his marketing after the midterms to minimize his original base in favor of minorities that by and large would never support him anyway, which, divided the nationalist movement against itself by not fully commiting to nationalism. He redirected much of supporter's energy into supporting neoliberalism and/or Qanon bullshit, and to top it off, he has decades-old connections to the same globalist elites that he claims to fight. Lost his re-election in a way that he could have easily prevented. And now after 4 years of this, he announces his intent to do it again.
And based on how he acted when he had control of Congress, it is very unlikely that a second Trump term would have a different result from the first.
I can't be the only one who thinks that something stinks here.
I'm not saying it solves anything, I'm just explaining what I believe is the psychology behind this phenomenon. Even those that sometimes declared Trump is controlled opposition or tended to criticize him, cheered for him when push came to shove.