Tufts University asked an academic what the financial results were for the UK: "The British GDP has been reduced by 6–8%, business investment has been reduced by 12%, and trade volume has been reduced by 15%, compared to what it could have been if the U.K. had remained in the EU." https://now.tufts.edu/2026/06/08/10-years-after-brexit-vote-...
Which is pretty much aligned with what more level-headed people predicted would happen, if my memory is correct. There was a strong push for UK to leave EU, but it was more based on emotion than rational. Of course the 'right' used the narrative of prosperity to get votes, but it never really made sense economically to leave the strong economic power of the EU and try to be independent again. The UK is not the empire…
Of course this was painted as "project fear", and Michael Gove famously said that people had had enough of experts.