“Fantastic” and “incredible” are signature words in the prime minister’s surprisingly limited vocabulary. But that exuberant comedic optimism that won him the election is wearing perilously thin. Real life will eventually crash in on Brexit fantasies, but when? How long can people stay in that alternative universe where dreams of sovereignty blot out what’s all around them? The religious down the centuries often inhabited dream-worlds of phantom heavens: Brexit voters can hibernate inside their own virtual reality – but not for ever. The deal Boris Johnson struck with his withdrawal agreement, the signing of which he called “a fantastic moment”, and sold to voters at the election, is now repudiated. Negotiations turned nuclear last week. If this was once brinkmanship, breaking the law by unilaterally revoking the treaty, no deal seems to have become his preference. Fear of resurgent Faragists weighs more heavily than his justice secretary’s threat of resignation, his chief legal civil servant walking out or seething Tory MPs, whose full strength we won’t know until final votes next week. But they are now backed by David Cameron, and four other former prime ministers. The blame-shifting strategy plan is being rolled out: note how Johnson in the Telegraph accuses the EU of planning a food “blockade”, plainly preparing the way to scapegoat filthy foreigners for the catastrophic consequences of a no-deal crash-out. The closer that disaster approaches, the clearer the reasons why Brexit is a self-harming delirium. Beyond economic damage, the greatest injury is and always was at the Irish border. No deal means that border must close: the EU single market can’t tolerate a flapping open back door. Brexit always risked the Good Friday agreement, so a trade border down the Irish Sea was the only alternative: a bad one, but as the Financial Times revealed, Johnson was briefed fully on its consequences. It means Northern Ireland obeying many EU rules. To prefer risking a rekindling of Irish border passions is a wickedness too far. The former attorney general Geoffrey Cox says ministers breaking the law causes “unconscionable” damage to the UK’s international reputation. But as the new cabinet secretary, Simon Case, pronounces that ministers breaking international law doesn’t breach the ministerial code, Johnson shows he has picked his ideal lackey. The spectacle of Conservatives – yes, Conservatives – dying in a ditch for the unfettered right to pick winners for state aid is a bizarre perversity. Where was that needed state investment in the last decade, when Germany, within EU rules, spent three times more on state aid? We could have spent plenty more on research and development but didn’t. For added irony, the vaunted new Japan free-trade deal commits the UK to tougher state aid restrictions than the EU’s: watch every new trade deal blow away more “sovereignty” fairy dust. Look what damage Brexit has already done. LSE research shows GDP at 2% lower than it would have been, with the Brexit vote leading to a £870 loss per household. But like many Brexit effects, that’s a frog-boiler, not ripped from pay packets before our eyes. As Thomas Sampson, LSE associate professor of international trade, says, Covid-19 is a gigantic short-term shock, but Brexit does the long-term damage. The motor industry warned on Monday that no deal would cause a £100bn “catastrophe”, as cars are hit with a 10% tariff and vans 22%. No deal would end certifications that allow billions of pounds’ worth of chemical exports to the EU. Financial services are creating new footholds in Amsterdam, Paris or Dublin, ready to take flight with their high-paying, tax-yielding jobs if there’s no deal: a tipping point that may leave London no longer a big player. Road haulage is just one of hundreds of industries that would lose licences and professional certifications to operate in the EU. As for that food “blockade”, it could be entirely of Britain’s own making. I am told it’s entirely impossible for 50,000 new customs officers to be hired and trained for still un-built port checkpoints with an un-built new IT system. A plan for 29 lorry parks speaks for itself of the chaos expected: fresh vegetables will be “blockaded” by Johnson’s own folly. Expect food, medicines and all those essentials stockpiled last time round to be in short supply. How will the politics play out? The government hopes Covid calamities mask the effect of a Brexit crash-out. The worst effects will grow over the years, while lorry queues and shelf shortages may last only a few months. Ardent Brexiters will be undeterred by anything, but the government-induced mayhem of Johnson and Cummings’ permanent revolution is a vote destabiliser. How will Brexiters tolerate the no-deal destruction of British fishing and farming, sunk by tariffs? Economically negligible, but politically red hot. Take Andrew Varga, managing director of Seetru, a Bristol manufacturer of industrial safety valves with £11m turnover that employs 130 highly skilled staff. This lifelong moderate Conservative voter is now in “deep gloom”. “I can see no upside,” he says. Brexit has already cost him much EU business. But isn’t he escaping EU red tape? Just registering 30 ranges under both the EU and new UK kitemarks will cost him £75,000. Any delay in just-in-time deliveries across the channel will see his products axed from customers’ supply chains. “I lose sleep over that.” His global exports are growing as before, “but we’re 30% down from where we would have been in the EU”. Brexit “has a psychological effect on their decisions”. Will he be voting Conservative again? “I’m past caring what Boris Johnson has in mind. The damage is done already. I like Keir Starmer – he visited the factory and he’s credible and serious. If the Corbynistas don’t reappear then I’ll vote for him.” By chasing after red-wall Brexit voters, No 10’s antics may lose it many more votes it takes for granted. • Polly Toynbee is a Guardian columnist