The differences here are over values not facts.
Specific examples aside, the EU buys into the idea that you can harmonize society with the right laws. The Brits were never going to be okay with that. It's a continental idea and inimical to common law. This is a country where they don't have ids. They passed a law to create ids but then it was repealed and the ids were destroyed. You can read Notes from a Small Island for more about this specifically British attitude. Or Orwell: https://www.orwellfoundation.com/the-orwell-foundation/orwel...
Anyway, there are good reasons for not being in the EU. Low voter turnout. Austerity policies (Boris Johnson is part of the conservative movement to the left on economics). The disastrous decision to share a currency (which plenty of economists warned against).
But the main reason the EU is going to atrophy over the next 50 years is that European identity is illusory. It's something for well-off cosmopolites. That doesn't make it wrong but most people in these countries are not a part of it, though they might go along when times are good. Moreover, as Hobbes put it, "covenants without swords are but words". Countries are about shared land, shared borders, and a shared duty to defend that land. The kind of people who feel European identity (or consider themselves "citizens of the world") are uncomfortable with this bloody-mindedness (and not for no reason). But nations are martial compacts and, for all of our discomfort with that, they are the best way we have of ensuring rights. The UN and EU have proven ineffective at that. In a crisis (like covid) Europeans will act singly as countries or not at all.