it's rooted in the self belief that we did do better than the continentals in the past so we can do equally better than them in the future.And the New Statesman weighs in with this
https://www.newstatesman.com/politics/economy/2019/01/why-uk-cannot-see-brexit-utterly-utterly-stupid
Why the UK cannot see that Brexit is utterly, utterly stupid
The British press helped condone austerity. It's now blinding us to the stupidity of Brexit.
It's also easy to believe that crises in Europe are due to corruption and there's a belief that we don't have corruption here.
BTW, plenty of my friends voted out and as a rule, we never speak about brexit.