This is certainly common "wisdom" now, but in 2016 I can remember very very clearly that the argument was that things would economically more prosperous when the UK was outside the European Union.
Any suggestion that this wasn't the case was immediately branded "project fear", called lies and discredited.
A question for me here is this: if your thinking is accurate here, and we're significantly poorer post-Brexit, was it right for 52% of the country to take resources away from the remainder, possibly lots of resources, in order to support their goals of national identity?