Leaving the EU was never about economics, which is why ‘Project Fear’ failed so badly. Many people who voted for Brexit would have been happy to stay had the project actually been about economics, which it was for many years. But that all changed with the drive to a Federal Europe. In truth the EU is in a dreadful mess and anyone claiming otherwise is fooling themselves.
It’s likely to be many years before any proper judgement can be made about the pros and cons of leaving, but there are many in the establishment, including the civil service, who want Brexit to fail while some of the EU countries have behaved like petulant schoolchildren.