Technically the EU was clear that the single market was a red line for them, and because the UK (under the Conservatives) was unwilling to cede fishing rights and regulatory autonomy, which were red lines for us, neither party moved on their position. So I’m not sure it’s quite as one sided as you’ve made out!
The biggest problem is that the British public voted for Brexit. And that’s in no small part because there was no coordinated ‘remain’ campaign. Labour under Corbyn, in my mind, are as to to blame for this as anyone. That and the Westminster/middle class complacency that the public wouldn’t actually vote for it…
Historically we (the UK population) have been ambivalent about the whole EU project. So the ‘leave’ messages were able to land without much critical thinking or counter argument, and the ‘remain’ campaign needed to work much harder to get the message across. It failed to do so, partly because of conservative / liberal complacency.
And let’s not forget for the low paid the short term benefits of Brexit, driven by labour shortages, became apparent very quickly. What used to be minimum wage jobs very quickly paid more. Remember when supermarkets got into a cycle of saying how much more than minimum wage they were paying? Of course, the longer term economic impact of Brexit, followed by Covid, increases in the living wage and labour costs in general have led to more automation and fewer jobs. But we still have pretty much full employment, as defined by those who want to work being able to. Though, the recent tax on employment in the budget will change that I am sure.
But, we can’t easily change what has been done. And even if we can it will take time. We can however still make the UK a more attractive option for investment, but sadly the first budget of this government made it even less attractive.