Behind the Curtain: Trump's big, unfixable, glaring glitch

• No practice, pleas or sage advice keep Trump from being Trump.
• It's a feature — not a correctable bug.

The big picture: There is a straight, illuminating through-line from Trump's post-assassination-attempt convention speech and his debate performance Tuesday night.

• Go back in time. Go back to the seconds after he was shot at in Pennsylvania. The moment Trump rose, ear bloodied, fist held high, American flag flying behind, and mouthed: "Fight!"
• It was an iconic moment, an unforgettable image, a political memory money can't buy. And, Trump's team believed, a sure-bet ticket to winning in November.
• All he had to do, they told him, was use the moment to say he took a bullet for America, and felt like a changed man ready to pull the nation together. For a few days, he did ... until 28 minutes into his prime-time convention speech on July 18.

Trump knew — and was told — he could walk off the convention stage up double digits in the polls if he exploited the assassination attempt and cut the grievance crap.

• But just like Tuesday's debate, he simply couldn't help himself. He went on for 60 more rambling minutes in that convention speech, rehashing his greatest grievance hits.

The same pattern unfolded at the debate, like clockwork. You saw it in the first 20 minutes or so: Trump was calm, confident, self-controlled in discussing the economy and what he could deliver for voters.

• Then Harris went for Trump's obvious ego soft spot: crowd size. You don't need to be Freud to know Trump is sensitive about his fans — and their attention and affection. Advisers told him she'd bait relentlessly on this or similar topics. Don't bite, they counseled.
• He didn't just nibble at the bait. He crushed it like a starving, roaring river salmon. He was on a wild run the rest of the debate.

Behind the scenes: A top adviser, asked about the reporting in this column, said the team lets Trump be Trump.

• "Nobody has tried to tell President Trump to be anything other than his genuine self," the adviser said, insisting on anonymity. "That's why we have been so successful so far, and that's why there has been harmony on this campaign. We're not trying to put him in a box. We want to amplify his strengths and use that as guidance for what we do."
• The adviser added that the debate "went very well — just ask the actual voters" (a reference to conversations with undecided voters by the N.Y. Times, BBC and Reuters).

In an alternative world, one that advisers tried to create with ad hoc debate prep sessions (which his campaign called "policy time," since Trump doesn't think he needs debate practice), he would have calmly turned every question against her.

• He was told to repeatedly ask why Harris hadn't used her power as vice president to do all the wonderful things she promises today. Taunt and bait her on her vice-presidential record, he was told. Make her own the border, inflation, crime, trouble overseas.
• He was told to repeatedly remind viewers that Harris wants to focus on the future because the present is more bleak and her past is much more liberal than she presents today. Simply ask viewers: Do you feel richer and safer today than you did under Trump?

• He was told to hold her accountable for the deadly, hasty withdrawal from Afghanistan. Yet when the moderators teed up that softball twice, he swung at other topics.
• It wasn't until the closing minutes of the debate that he seemed to follow that advice. By then, the damage was done.

Four reasons Trump cannot and will not change, according to friends and advisers:

1. He's haunted. He can't stand being seen as a loser. So it's impossible to fully admit he didn't win in 2020. He looks to distractions like crowd size and adoring coverage for solace. So, seemingly silly taunts — like Harris' "people start leaving his rallies early out of exhaustion and boredom" — hit deep.
2. He falls for fake news. For a guy who made "fake news" a household term, he falls for it often and easily. It wasn't hard to learn that the allegations of Haitians eating pet dogs and cats were silly and wrong. But far-right activist Laura Loomer was on the plane ride to the debate with him, egging him on.
3. He's old. A wise man told us three types of people never change: Old guys. Rich guys. Guys with their names on the building. So the chances that Trump — a 78-year-old, self-proclaimed billionaire with his name on buildings, bottles and golf courses — will change are, um, nil.
4. His bubble lies to him. All politicians live in self-protective bubbles. But Trump's, which extends from his social media cocoon to his Mar-a-Lago luxury, is almost impossible to penetrate with hard truths. There's always a Loomer to tell Trump he's winning ... even when he's not.