It's gonna take a very long time. At the moment it's a bit like with certain sections of the right in the US, people are totally in denial. I said this before in another context, but in the past, people would look at what is happening and then the Right and Left would argue with each other about what it meant, but now we have a new situation where you get the news and videos and so on, and the far right get stuck in to that and argue with reality about whether it's happening.
Just for one example, supermarkets are having issues with their supply chains, a particular issue (which fair enough I never saw mentioned before it arose) is that in the past, suppose a lorry makes a delivery from Poland to Birmingham and then goes to, I dunno, Manchester say and picks up another load there to take back to Poland, it would also find something that needed to go from Brum to Manchester and take that so it never travelled empty and I think that the nobody really calculated on the missing trip in the middle, they knew that the goods movement from Poland to UK and from UK to Poland might no longer happen, but now they are suddenly realising that there is no-one there to do that little run from Brum to Manc and this is a big disruption.
But the point is; supermarkets have said "our supply chain has been disrupted by Brexit and so sometimes many of our shelves are empty and some goods are not available", also you have the association of hauliers announcing that we are 100,000 lorry drivers short of what we need, you have the government saying that the army is on standby to help move food around (although it's not gonna help cos there aren't that many and they don't have the right kind of trucks or training or blah blah blah) and then finally you have loads of people taking pictures of empty shelves in their local supermarkets an being upset that they can't get what they want, and if they can it's often lower quality, and the prices are increasing.
So, how do Brextiers respond to that? Well, one of the standard responses is "My supermarket was fine this morning, there is no food shortage, it´s all a Remoaner lie" - hilariously there was one where they all went mental "That photo is obviously not in the UK, the writing on the shelves is in foreign" cos Brexiters don't know that there is a country in the UK called Wales where they speak Welsh.
And then you have a slightly (and I mean very slightly) more sophisticated response where they blame covid for the shortages. Obviously immediately exploded by the fact that it is happening in the UK, but not in the EU.
So at the moment you have food shortages being denied, companies closing or moving abroad is dismissed as "talking the UK down" and the one big factory which did open in the UK was celebrated like crazy even when it emerged that the government paid it a massive subsidy/bribe to do so and so it was no real gain for the UK.
So at the moment when people are literally denying the actual facts of the situation, it's difficult to see how people can start talking about why they are happening and whether they were wrong to vote for the thing that caused them.