By Chaminda Jayanetti
They didn't listen and they didn't learn.
For years, Corbynites were warned that their leader was electorally toxic. All evidence showed that voters not only didn't see Jeremy Corbyn as a strong or credible leader, but didn't see him as trustworthy either - supposedly one of his strong suits.
During Corbyn's four years as leader, his leadership ratings were only strong for a handful of weeks in the immediate aftermath of the 2017 general election.
This became a kind of creation myth for his supporters - proof that he could upend the supposed rules of elections. No matter how bad his ratings were during the tabloid-strewn years between elections, they could polish his profile for the big campaigns.
Last night the myth was blown to smithereens - and Britain's future prospects with it. Labour's catastrophic night saw the party sink to a worse defeat than 1983, with the Tories securing their largest majority in more than 30 years.
Labour went into freefall in its Leave-voting former heartlands in Wales, the Midlands and Northern England, with the Tories obliterating the so-called 'red wall' of target seats, even ousting veteran left-winger Dennis Skinner in Bolsover.
But Labour also failed to win seats in southern Remain hotspots. It's easy for Labour to blame the Lib Dems for splitting the anti-Brexit vote in Chipping Barnet, Hendon, Wimbledon and - most egregiously - Kensington, where Sam Gyimah ran a self-abasing campaign against Labour MP Emma Dent Coad and saw the Tories get in.
But ultimately, people only voted Lib Dem because they chose to. They simply didn't want to back Corbyn in sufficient numbers - both Remain voters and Leave voters, London and Not London.
Did Labour's second referendum pledge alienate Leavers? Almost certainly. But had they not made this pledge, they'd have alienated Remainers instead.
Corbyn, alas, alienated both.
The balancing act was never an easy one for Labour, but they made it as hard for themselves as possible by sticking with the worst possible salesman, whose indecision on Brexit brought derision from voters, aside from concerns over his associates and handling of anti-semitism.
Corbyn himself is not a megalomaniac. As Labour's polling and Brexit position slumped during 2019, it's plausible he would have agreed to stand aside if asked to by his key backers.
But instead the Corbynite machine at the top of Labour kept doubling down on this dubious bet. Seumas Milne, Andrew Murray, Len McCluskey, Jon Lansman - old tankies with fat salaries or monied families - formed a praetorian guard to protect the man from whose leadership they drew such influence.
For all the talk of a grassroots mass movement, the dirty little secret of Corbynism is how many of its senior figures are wealthy or even dynastic. How easy it is for them to think in terms of the long view of history when they won't be affected by what happens in the meantime.
The people who'll be affected aren't just members of the public at the rough end of government policy - it includes Corbynites themselves. Those party activists who are actually working class are a much rarer presence in Corbynite power circles. It is perhaps ironic that a movement nominally dedicated to breaking down class barriers and closed family networks is itself rife with such barriers and networks at its highest levels.
These people will fail upwards. They have the money or the contacts to land softly and effortlessly rebound as Labour falls apart and the country crashes into Boris Johnson's hard Brexit.
For everyone else, there is likely a decade more of Tory rule coming, together with unprecedented strains on the Union and the constitution. To give one example, judicial review - a crucial tool for people to defend their rights against the government - is likely to be curtailed.
Far from reflecting on the causes of Thursday's electoral disaster, online Corbynites have already defaulted to blaming centrists, Remainers, the media - pretty much anyone but their leader.
Which is strange, given that Corbyn has already announced his departure and the second referendum commitment won't survive Britain's exit from the EU, making the argument moot.
Instead it confirms a culture of deflection and blame that led the Corbyn project directly to Thursday's night's ignominy.
Corbyn has said the party now needs to reflect. The Corbyn machine is unlikely to pause for such reflection, however. It'll just creak back into action to find a favoured protégé to take over the reins and keep the six-figure socialists in place.
Because Labour doesn't need power to save the failed scions of privilege from unemployment.
Chaminda Jayanetti is a freelance journalist. Follow him on Twitter here.
The opinions in politics.co.uk's Comment and Analysis section are those of the author and are no reflection of the views of the website or its owners.