We all have a “terrible boss” story or 10. My best is from a few years ago when I found myself out near Erbil (before Isis emerged) with a tiny film crew working on an independent Kurdish film. Our director was a fascinating case study in what happens when monumental arrogance and total ignorance combine in one person. He would often call for things like a “medium wide close up” – which is not a thing – and then get angry when asked for clarification. On one particularly memorable day, we found ourselves standing on top of a mountain in freezing conditions explaining that the sun was not the moon.

We went out there having only seen half the script, it being written (allegedly) but not yet fully translated into English for the crew. Two days after our arrival, the director described a scene in the second half: “Children streaming over the mountains from all directions, and then in the distance, explosions.”

Our four-man crew looked at each other, trying to work out what was going on. “How many children?” we asked. “At least 400.” Four hundred children and pyrotechnic effects in the mountains of Iraqi Kurdistan. OK then. We tried to gently figure out if he knew the magnitude of what he was asking, or maybe had a second unit hidden somewhere we didn’t know about.

“Where will the children come from?”

“I will just go into schools and get them.”

“How long have you scheduled for this?”

“One afternoon. Easy.”

There was a word we’d throw around casually while out there, “crazy”. The entire thing was so baffling to us, at turns both hilarious and utterly terrifying, that it seemed insane.

As Trump ascends to the throne of god-king of the US, the desire to call him “crazy” has taken hold. Armchair psychiatrists take to every media outlet to inform us that he’s an aberration, a madman, dangerously unhinged. Even if you ignore the problematic nature of trying to diagnose mental illness at a distance, this easy mantra is unhelpful. I don’t deny that the Trump phenomenon is in many ways much worse than what’s immediately preceded it in the US, but what it isn’t is unrecognisable. What it isn’t is insane.

We all know Trump. We’ve worked for him, served him in a restaurant, dealt with him in a call centre. He’s the boss who emails you at 4.30pm on a Friday, doesn’t pay overtime for the work you do all weekend, and then takes credit for it on Monday. He’s the customer who refuses to tip because you didn’t smile when he called you “darling”. He famously stiffs contractors if he can get away with it. He is “gauche even by the standard of rich people in Manhattan”. You only have to listen to him for five minutes to know that he is intimately familiar with the taste of a waiter’s testicles rubbed on to his $200 filet mignon.

As Professor Allen Frances, the man who wrote the official definition of narcissistic personality disorder, points out: “He may be a world-class narcissist, but this doesn’t make him mentally ill, because he does not suffer from the distress and impairment required to diagnose mental disorder. Mr Trump causes severe distress rather than experiencing it and has been richly rewarded, rather than punished, for his grandiosity, self-absorption and lack of empathy ... His psychological motivations are too obvious to be interesting.”

Indeed, what differentiates Trump is not his behaviour, but merely the height to which he has risen. The world is full of self-made used car salesmen harassing their secretaries in local government. Trump is Mayor Quimby – a character who dates back to 1990 – but this time for the whole of America.

Bad bosses are ubiquitous, and they are rarely mad. They are the result of systems that actively select for their bad characteristics. Overconfidence, a widespread cognitive bias, is selected for in managers because it is easily mistaken for competence. Overconfident people generally have excuses for their failures (think of Trump crediting everything that goes well to his natural talents, and blaming everything that goes wrong on his underlings, the media, the moon etc). Bosses also select people like themselves for promotion, so our cultish deference towards entrepreneurs, managerialism and “disruption” creates work cultures where aggression and overconfidence become the mark of a “good leader” regardless of results. Men with loud voices and firm handshakes can rise even if their actual performance is mediocre at best.

Trump’s aggressive, sexually predatory misogyny is also not uncommon. We have a system of values entrenched over millennia that encourages men to be aggressive and dominant or die trying. David Davis this week used the old sexist jibe that Diane Abbott was too ugly to sexually assault, we see this kind of thing all too often in conversations men have about women because we never unpack the deeply grotesque and dehumanising entitlement that underpins them. This is not the same as Trump’s “grab them by the pussy” comments, but it certainly lives on the same street.

How can it be “mad” to perform in a way that is encouraged and rewarded? Nigel Farage, a man cut from the same cloth as Trump, is a talentless blowhard wearing clownish “man of the people” drag, and he is given endless media coverage – why would he choose to be anything else? Why would Trump, who has been elected to the presidency on the basis of an incoherent word salad sales patter honed over decades of grifting, ever behave any differently? We give them what they want when they behave this way.

Trump’s ascension is not the result of a “depraved madman” accidentally ending up in power, but of basic, widespread and wholly predictable cognitive biases. Our rush to brand him as an aberration is also a bias – we wish to believe that we couldn’t have seen this coming, that we do not ourselves contribute to the systems that make the Trump administration’s sadistic policies possible. It is an act of self-protection. Trump the madman is a soluble problem: we just impeach and replace him. Trump the perfectly sane result of a deeply broken system is far more terrifying, which is why we are putting so much effort into inventing reasons it cannot be true.