It is plain that some Brexiters do not care why people voted for Brexit, as posts on this thread demonstrate.

I personally believe that some Brexiters did believe that some people would be better off: some people imagined that EU workers in Britain would be kicked out, resulting in more jobs being available for British people: I know this because on the day after the referendum I heard a Brexit voter saying this to somebody wearing Asian dress (not logical I know, but it happened).

Some Brexiters believe that at least some business people will make more money after Brexit because the 'red tape' which they see as holding business back can be got rid of, stuff like workers' rights, holiday entitlement, product standards, environmental rules and so on. The Leave means Leave web site mentions pharmaceuticals being hidebound by regulation, which suggests that some pharmaceutical firms want to be selling stuff that doesn't meet EU standards. But of course if you want to sell stuff to the EU it will still have to meet EU standards.

So these economic predictions don't really address the issue of who will be paying the price for UK lower performance as some business people clearly expect to do better. Given the present government my guess is that it will be as usual the lower echelons who will end up paying the lion's share of any price.   

But a lot of the arguments were about 'sovereignty', and 'control', which you cannot really put a price on.