What evidence do you have that almost 100% of all economists, most business leaders and the government itself actually say what you say they say?
I can't believe that after over 2000 posts, many of them linking news items confirming what I say, that you are asking that question but, here goes...

From The Economist
The link does not refer to "almost 100% of economists". It does mention "most economists", which could be as little as 51%

From The Caterer
This page does not give a forecast for Brexit, it details costs already incurred, and plans currently being laid.

From CNN
This page deals (mainly) with the expected results if we follow Mrs May's deal, which does not have much support from those who voted Brexit, as it does not get us 'out'.
It does go on to give forecasts for a 'no-deal' Brexit, but based on the prognostications of the Bank of England. A department which has so far failed to cover itself in glory with its predictions.

There are hundreds, if not thousands, of such links. I have yet to see any saying we will be better off.
If your hundreds, or thousands, of such links are of the same standard it is hardly worth bothering, as they do not support your statements.
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And yes, I can see the possibility of some hardships following Brexit (assuming it happens) but I view the possible benefits as being of greater long term value. (in answer to DMcG)