For many Brexiters, the European Union was not an institutional arrangement that eased trade, immigration and political disputes; it was nothing short of a conspiracy to sap money from the United Kingdom to Brussels, construct an EU army, or help spread Islam across the continent. This thinking underlies the political project to leave the EU. As they are not grounded in truth, these narratives have produced Brexit’s lengthy saga of political ineptitude.

Magical thinking bred magical thinking. Brexiters indulged fantasies about completing an “easy trade deal” before we left the EU or waiting for German carmakers to ride to their rescue when the chips were down. Meanwhile, the EU focused on getting what it wanted: a legally binding deal on money, citizens’ rights and the Irish border issue. After leaving, Britain will be bound by EU laws and decisions for at least the next two years while the government attempts to negotiate a trade deal with the UK’s largest trading partner.

The thread running through this sorry episode is that of political misjudgment by the Brexiters. It is naive to think that one of their own could have made a better fist of the negotiations than Theresa May. She peddled nonsense about a pure Brexit until reality struck in Brussels and she was forced to make compromises. Contrary to the propaganda, the EU was no pushover. The UK decided to leave the club and there was a simple trade-off to be made: to gain access for its goods but to be outside the customs union, the UK needed to replicate all the features of the tariff regime.

The next stage of the negotiation, if we ever get there, will see ministers trade access to the market in European services for free movement of people. Brexit will be like a divorce where the adulterer returns home because they have nowhere else to go. Mrs May’s retreat to sanity is now viewed as a treasonous betrayal. The prime minister is not blameless. She had sung loudly from the same hymn sheet as the true believers, no doubt for fear of being accused of not having her heart in Brexit. But no one can square this circle. The Brexit revolution might eat her as its first victim. One of her tormentors, Jacob Rees-Mogg, is being lined up as the second.

In a new book, Conspiracy Theories and the People Who Believe Them, academics say EU conspiracy theories laid the blueprint for the Brexit vote. Should the UK leave the EU, the authors note, the “conspiracy theories that motivated leave voters will have shaken the very foundation of the international order”. These are not charges made lightly, but hard Brexiters have long traded in falsehoods. They are now adopting dangerous tropes of the far right.

There can be no disdain for those who believe Brexit’s hucksters. The past decade has seen voters deal with economic and constitutional crises. People have become used to challenging authority in a good way. But they have also become suspicious, notably after their leaders obfuscated about big decisions such as going to war. They have become susceptible to the idea that life is not full of cock-ups but conspiracies. Such theories are harmful, even deadly. Exposure to one such myth saw fewer children vaccinated, and ministers have now acted to curb its transmission on social media. One way to inoculate the public against Brexit delusions is to be honest. Leaving the EU is a mistake and there will be a cost associated with it. European leaders will not pay for Britain’s decision to leave. The UK is in a hole. Voters must have this explained to them by politicians who can stop digging so the country can get out and move on.