Heres a simplistic analagy. Say somebody that is a teacher decides to re-train as a structural engineer. Yes he might or might not be better off with a different career -but until trained he can only take any job because he still needs to earn.
With a no deal Brexit, we leave every single trade deal, Brexiteers may think there are better deals out there in the world, but they dotn happen overnight, they take years to achieve.
What happens to UK trade in the meantime? -its obvious the UK will have to accept any deal it can, starting with a position of most favoured nation status (which will wreck the UK agriculture and industry).
That is the major consideration lacking in the Brexit argument -they are all focusing on leaving the 'wicked EU', but havent worked out the destination. Trade deals are a major issue if a country is already trading.