I'll be fair to Brexiteers here:
https://www.economistsforfreetrade.com/
However, more objective economists, while acknowledging that unilateral global free trade might (again, might) benefit the UK more than remaining in the UK in the long run, that still raises the question of whether it's worth tanking the UK economy in the short-to-medium-term for what might (again, might) bring a little bit more benefit to the UK economy in the long run than remaining in the EU. To tank an economy in the short-to-medium term, we'd generally expect a major return on investment in the long term. Even economists for Brexit acknowledge that that wouldn't be the case, that it might just break even, maybe bring a little more benefit, maybe a little less, but certainly not the overwhelming benefit that would warrant such short-to-medium-term chaos.
That said, if the the Brexiteers are determined to bring about Brexit, then at least have a plan in place to make the best of it. They don't even have that.