A week after the release of a book depicting him as not intelligent enough and not mentally fit to be trusted as commander-in-chief, Donald Trump has done it again. On the same day he cancelled a visit to London to open the new US embassy there, a move many interpreted as an attempt to avoid embarrassing protests, he embarrassed himself further by demanding to know why the US deigns to accept immigrants from “shithole countries”.

Before this latest outburst, the White House had spent a week trying in vain to rise above the account of Michael Wolff’s Fire and Fury, which uses the words of people in Trump’s White House and inner circle to argue that Trump, in the alleged private words of secretary of state, Rex Tillerson, is a “fucking moron”. Having failed to block the book’s publication and instead hastened it, the White House pivoted instead to denigrating Wolff and one of his primary sources, the former White House chief strategist and Trump ally Steve Bannon.

Trump pursued the mission with both anger and enthusiasm via his favourite medium, Twitter, slamming the book as “really boring and untruthful” and dismissing Bannon as “Sloppy Steve”.

Besides reinforcing his image as a temperamental, ill-informed man-child, Trump’s counter-attack misses the point. Even if Wolff is a huckster peddling dubious quotes, as more than a few journalists claim, others have been spreading the message publicly and privately since the day Trump took office.

Chief among them, via his own actions and words, is Trump himself. But there’s also Democratic senator Jack Reed, who in July 2017 told his Republican counterpart Susan Collins, “I think – I think he’s crazy. I mean, I don’t say that lightly and as a kind of a goofy guy.” Collins responded: “I’m worried.” Republican senator Bob Corker, the chair of the Senate Foreign Relations Committee, first said that Trump “has not yet been able to demonstrate the stability nor some of the competence that he needs to demonstrate in order to be successful” and later called the White House “an adult day care centre”.

The cabinet, too, are more than worried. Besides Tillerson’s reported contempt, Trump’s secretary of defence, James Mattis, and his chief of staff, John Kelly have reportedly made a pact that one of them will be in the US at all times.

But in Wolff’s account, the foremost figure to question Trump’s faculties is Steve Bannon, the hard-right ideologue who arguably propelled Trump to victory.

Treasonous and unpatriotic

Wolff depicts a Bannon out for himself and his agenda, even at the cost of tearing down Trump and his family. “Javanka”, the husband-wife team of Trump’s son-in-law Jared Kushner and daughter Ivanka, meet with Bannon’s unbridled derision: Kushner is financially compromised, including by Russians, and Ivanka is “dumb as a brick”. The elder Trump himself, meanwhile, is a pliable simpleton.

But far more importantly, Wolff’s Bannon inserts the Trumps into the middle of the alleged collusion with Russia during the 2016 campaign. Donald Trump Jr., Kushner, and then-campaign manager Paul Manafort are “treasonous” and “unpatriotic” for a June 2016 meeting with three Kremlin-linked envoys in Trump Tower in New York City, arranged by Trump Jr. to discuss Russia’s provision of material damaging to Hillary Clinton.

In Wolff’s rendering, Bannon thinks the ultimate downfall of Trump and Co. will be revelations of Russian financial input into the campaign: “It goes through Deutsche Bank and all the Kushner shit. The Kushner shit is greasy. They [Mueller’s team] are going to go right through that.”

After the book dropped, Bannon did not deny any of his statements. Under pressure from his billionaire backers the Mercer family, he clarified that the words “treasonous” and “unpatriotic” refer only to Manafort, who is already under indictment on financial, tax and lobbying charges related to the Trump-Russia investigation.

Bannon has become the most conspicuous casualty of the Fire and Fury fallout, not only dismissed as “sloppy” by Trump but now ousted from his position at far-right soapbox Breitbart. But even with Bannon mostly stripped of his influence, the complaints against Trump raise a disturbing question: why are so many people who think Trump is mentally unfit still willing for him to remain in office?

The answer is that no matter how unstable and vacuous he may be, Trump is a very useful vehicle for other people’s ambitions.

The useful idiot

Even after his supremely unedifying first year, Trump still serves as a conveniently empty vessel for all manner of enablers. Having resuscitated his career after six bankruptcies by playing a businessman on reality TV, he now plays the role of chief executive so industries can get pesky regulations rolled back.

As he keeps up his stream of offensive, irresponsible pronouncements, GOP legislators put up with it so they can finally secure their $1.5 trillion tax giveaway. And as white supremacists proclaim their moment has come: as David Duke, former KKK Grand Wizard, explained at the violent Charlottesville march in August 2017: “We are going to fulfil the promises of Donald Trump. That’s what we believed in.”

As long as Trump serves that purpose, it does not matter how many conflicts of interest he has, how many women accuse him of sexually harassing or assaulting them. It does not matter how many memoranda or constitutional clauses he does not read or understand. And it does not matter how many Russians he and his inner circle might have met and assisted.

But Trump’s usefulness might well expire when Robert Mueller completes his work. That could be sooner than many people would like – with Manafort indicted and former national security advisor Michael Flynn pleading guilty to lying to the FBI, the next probable target is Kushner – and from there, it’s only one rung up the ladder to Trump himself. Then again, Mueller’s probings could take months or years more to get there. Until then, this emperor’s new clothes nightmare continues with no end in sight.