Americans have felt let down again and again since the ’60s, with wars we shouldn’t have been in, occupations we shouldn’t have had, the bank scandals that were allowed to happen, and trade agreements that hollowed out manufacturing hubs. Then there was the devouring pandemic. Many Americans felt left behind, fooled by Republicans and disdained by Democrats.

All the dislocation was exacerbated by social media algorithms igniting anger, outrage, resentment, conspiracies and fake stories.

Trump is a human algorithm, always ratcheting up antagonism. He’s a personification and exploiter of all the things creating anxiety in people’s lives.

I sat through Trump’s rally in Madison Square Garden for eight hours, working my way through a box of popcorn, a large pretzel and two bags of peanut M&Ms. I was surprised when some commentators reacted with shock at some of the insults slung that day.

For me, it seemed like a pretty typical Trump rally: ugly, dark, crude, denigrating, racist, misogynistic. (Sid Rosenberg, a conservative radio host, helped kick things off by calling Hillary Clinton “a sick son of a bitch”.) Speakers included Elon Musk, RFK Jr and Tucker Carlson, who thinks a demon clawed him while he was in bed last year. It is frightening to contemplate how much power this gruesome threesome will have if Trump wins a second term. It’s unimaginable that RFK Jr, who doesn’t trust vaccines, could be in charge of health policy. Bobby Kennedy may not believe in vaccinations, but somehow we’ve been immunised against outrage.

Trump just keeps finding new ways to make America lurch backward; he has cast women back into back alleys on abortion. This past week, it felt as if every day, there was some new horror story about a young woman dying or nearly dying because doctors are scared of new legal strictures on reproductive care.

We’ll see if Madison Square Garden was a last hurrah or a harbinger of this crazy movement that cannibalises institutions and people and souls and spits them out and then replenishes its ranks with new Trump enablers.

The bizarro gathering was seen as a turning point by Harris campaign officials, who told reporters that they thought that the rally’s nasty tone had helped Kamala Harris with voters who decided late, underscoring her emphasis on the positive versus the negative, the light versus the dark.

It’s no surprise that Trump provided last-minute evidence of the character he lacks. As he said about being the protector of women, he will do it “whether they like it or not”. That’s the way it is with Trump and women – whether they like it or not.

I would have been more shocked if Trump had used his big moment at the Garden to offer a sunnier vision, to recall growing up in Queens, longing to get to Manhattan, to offer some humorous anecdotes from The Apprentice, filmed a mile away at Trump Tower, or to reminisce about Frank Sinatra, Muhammad Ali or iconic Garden sporting events.

But that would have been the human thing to do. And Trump doesn’t care about human niceties. He just wants to be the biggest beast in the jungle, to take whatever he wants in any way he can get it. At the Garden, an artist live-painted a picture, then revealed a pentimento of Trump hugging the Empire State Building, King Kong style.

Trump’s premier skill is an ear for the roar of the crowd – in person and in ratings. He will follow that roar anywhere and say anything to hear it.

Con men succeed because they tap into genuine yearnings in society. When Trump was a New York celebrity, he was famous for running his mouth, saying outrageous things, and engaging in a mutually beneficial gossipy relationship with the tabloids. Then he learnt the really dark arts. He began milking the emotions of Americans who don’t feel that things are working for them, who feel that the government is corrupt and incompetent, who feel that it’s them versus Washington.

There were two things Trump said to me during the 2016 campaign – when he was still speaking to me – that struck me as unusually honest. I asked about the incidents of violence that were starting to erupt at his rallies. Wasn’t he worried about that?

No, he explained. He liked it rough; it added an air of excitement to the proceedings, he said. (This barbaric side of him came out on January 6, 2021, as he watched television, savouring the violent scene he had egged on, saying about the rioters who wanted to hang Mike Pence, “So what?” He recently told Fox News it was “a day of love”.)

I also told him once that his persona was getting more belligerent and divisive. To me, he had seemed like a more benign, if crazily narcissistic, Macy’s Thanksgiving Day balloon of a figure in the New York real estate days. Why was the former pro-abortion rights Democrat going down such a dark and authoritarian path as a candidate?

“I guess,” Trump mused, “because of the fact that I immediately went to No.1, and I said, ‘Why don’t I keep the same thing going?’”

Trump can play it round or square, pro-abortion rights or anti-abortion, pro-TikTok or anti-TikTok, pro-crypto or anti-crypto. He has no philosophy except “What’s in it for him?” The only thread of continuity in his life is self-interest. He supercharged and retrofitted the Republican Party for his own benefit.

Trump told a rally on Friday that he’s always “tossing and turning, spinning around like a top” in bed at night, thinking about the problems in the world. I don’t think he wakes up every day worrying about the country and how to solve problems that people care about or how to soothe our raw divisions.

He wakes up obsessing over how to reward himself, his family, and his friends and how to punish his enemies. He wakes up plotting how to pit people against one another.

Government can produce a positive effect only if it’s run by people who are serious about government. And, as Harris said, Trump is an unserious man.