The UK is today poorer than it would be if it had remained
No it isn't! Living standards are increasing steadily, despite Tory depredations and being outside that trading bloc has helped hugely in sourcing energy at a time of wartime instability.
Even the city suffered unnecessary losses
And is growing again, after recovering from the failed attacks by Paris, Hamburg and Amsterdam. In fact the number of major companies trading in the LSE has increased and a couple of major ones have delisted elsewhere in the continent.
It weakened the UK
Again nonsense. It did weaken the ability of foreign companies to buy U.K. ones and has certainly weakened those companies (often state owned) from abroad who'd bid for and won infrastructure franchises but not delivered on the terms of those contracts.
Micron was literally begging for U.K. subsidy for the new reactors that the French bid to build at an unrealistic price with the intention of using EU structures to squeeze the real price later. That failed and the impact on EDF is such that energy costs in France are rising to pay for that.
They signed contracts with no intention of meeting them and now they're locked in.
Also we are nationalising buses, trains and steel in the public interest. That would not be possible were we still in that trading bloc.
This thread is however about the rise (reappearance?) of fascism in Germany. Not your delusions about trading blocs.