Some people are better off than others. But stating as a fact that the EU was no benefit for some people needs a supporting argument, since it can't be demonstrated empirically (as a counterfactual case).
I'm sorry, but that sounds like bullshit to me. You're implicitly assuming your conclusion by asserting without proof that the negative is counterfactual. Your mind might contain all the background knowledge you need to make any other statement sound incredulous, but in terms of discourse you need to reveal that information or let your own claims go just as unsupported as well.
Additionally, "no benefit for some people" is such a weak statement that you're bound to observe some contrary cases even if they aren't typical or representative. So at the limit I don't think you're making the right bets. But I would agree that the more evidence should be given. I would disagree that this evidence can't be empirical; it's obvious that it's a statement with empirical consequences, as we're speaking about elements of the world (people who live under EU policy in the UK).
Additionally, "no benefit for some people" is such a weak statement that you're bound to observe some contrary cases even if they aren't typical or representative. So at the limit I don't think you're making the right bets. But I would agree that the more evidence should be given. I would disagree that this evidence can't be empirical; it's obvious that it's a statement with empirical consequences, as we're speaking about elements of the world (people who live under EU policy in the UK).