One of the possible benefits, in fact the main potential benefit, is that the economy might do some serious rebalancing, such is the disruption of Brexit.
There will be a lot of pain and of course it will take such a long time a whole generation will most likely be stuffed, but there is a lot wrong with our economy. It’s mainly the inequality of course and I can’t see how Brexit reduces the wealth of the super rich and hedge funds - Brexit has made them substantially richer so far - while raising the income of the worst off and squeezed middle, but that might not be achievable without some kind of seismic shock to the economy. I suspect this is an unarticulated Hail Mary thought somewhere at the back of the minds of a lot of Leave voters. A sort of ‘something needs to change’ combined with ‘how can it be worse than now’ reasoning.
Well, it can certainly get worse (and has). That was the logical reasoning flaw, not to mention the poor appreciation of the factors affecting probability.