Boris Johnson concludes his Churchill biography with splutters against historians who insist the “story of humanity is not the story of great men and shining deeds”. The story of Winston Churchill, he cries, “is a pretty withering retort to all that malarkey. He and he alone made the difference.”

The story of Boris Johnson withers too. He is shrivelling Britain: making it cramped, poor and irrelevant. Modern historians may sniff at the 19th-century notion that “the history of what man has accomplished in this world, is at bottom the History of the Great Men” to use Thomas Carlyle’s words. The rest of us should not be so complacent and register the capacity of catastrophic men and women to change the world for the worse.

In his classic study On the Psychology of Military Incompetence, Norman Dixon analysed British generals who had led their men to pointless deaths from Crimea to Arnhem. How familiar his diagnosis feels. Dixon identified “overweening ambition dedicated to one goal – self-advancement” as a persistent fault; and that sounds familiar. Catastrophic men equated “war with sport”, he continued, and one thinks of Theresa May’s warning in 2016 that “politics isn’t a game.”

She surely had Johnson in mind. For him, it is a game and winning is all. Last year, he told the Democratic Unionist party that a border in the Irish Sea “would be damaging to the fabric of the union”. He jutted out what passes for his jaw and with a Churchillian boom thundered: “I have to tell you that no British Conservative government could or should sign up to any such arrangement.”

Last week, he signed up to “such an arrangement” because betraying his allies wins him the game of politics. Dixon noticed “an underestimation, sometimes bordering on the arrogant, of the enemy”. And one thinks of Dominic Cummings, so lost in his deluded machismo that he told EU countries that they “will go to the bottom of the queue” if they dared challenge the mighty Britain. A mere fortnight later, Johnson capitulated to Brussels so thoroughly the EU will no longer has to worry about the Irish border and can adopt the toughest of stances when and if trade negotiations begin.

No one should be surprised. It is an essential part of the catastrophic character that catastrophists do not learn from their mistakes or realise they are making them.

On the small matters as well as the large, political incompetents mirror military incompetents. Generals who display “a love of bull, smartness, precision and strict preservation of the military pecking order” are prone to lead regiments to disaster, Dixon wrote. Remember Jacob Rees-Mogg’s semi-literate instruction to his civil servants that they must address untitled men as “esq” when the practice is archaic. Or his insistence that they never use “hopefully” in his presence: even though the adverb has stood in for “I hope” for centuries and no serious linguist has the smallest problem with it.

Johnson remains in a bubble that feeds narcissistic delusions. The Tory press fawns over him because he is one of its own

Hopefully, you can see the links between disastrous generals and politicians. Catastrophic business leaders share their characteristics. Since the crash, there has been an explosion of interest in how unstable men and women are overrepresented at the top of business. The Australian Psychological Society’s congress heard a study of 261 senior professionals in the US, which found 21% had clinically significant levels of psychopathic traits compared to one in 100 in the general population. Once again, Johnsonian flippancy was in evidence. Psycho bosses treated business as “a game about getting where they want and having dominance over others”. Meanwhile, economists have demonstrated how overconfident managers fail to account for risks.

You might object that a democratic politician is different from Fred Goodwin at RBS or Adam Neumann at WeWork or a general who will not tolerate insubordination. They work in hierarchies, where it can be impossible for subordinates to criticise without risking their careers. By contrast, hundreds of thousands were on the streets of Britain yesterday making every criticism of Johnson imaginable – all of them correct.

For all that, Johnson remains in a bubble that feeds narcissistic delusions. The Tory press fawns over him because he is one of its own. His party toes the line because Johnson removes the whip from Tory MPs who challenge him and Cummings orders armed police officers to take away allegedly disloyal aides on the flimsiest of excuses.

Johnson’s career of failing upwards since he left Eton illustrates that overconfidence is class determined. In politics and so many other British institutions, you see mediocrities take jobs for which they are not remotely qualified, because wealthy families and a private education have emboldened them.

In all spheres, catastrophic men and women are united by an imperviousness to the suffering they cause. Even on the most optimistic assumptions, UK in a Changing Europe found Johnson’s “deal” will take £16bn from already dangerously underfunded public services and all who depend on them. (The pessimists believe £49bn will go.) The PM’s lack of concern for them is typical. Dixon described the siege of Kut in 1915 in what is now Iraq: an operation that led to 30,000 British and Indian army casualties. It distinguished itself, even in the First World War, for having no military purpose whatsoever.

When Maj Gen Charles Townshend surrendered, he was treated with the utmost courtesy by his Turkish opponents. They sent his 13,000 surviving men on a death march across the steppes that claimed 7,000 lives. Townshend’s concern “for the welfare of his dog was considerably more in evidence than for the welfare of his troops”.

Catastrophic men can determine the fate of armies, businesses and countries. Without fail, the catastrophes they bring are always someone else’s problem. I will grant Johnson this. There is every chance that history will say: “He and he alone made the difference.”

• Nick Cohen is an Observer columnist