The problem with this logic, is that it's the case that the UK is strong BECAUSE it's in the EU. Remove that, and you have lost one of the main strengths, and why many invest here.
Basically all the investment in the UK has dried up, lots of manufacturing, e.g cars is moving elsewhere. Even the Brexit supporters are moving their funds elsewhere, and businesses elsewhere, and this is BEFORE we have even left.
Why would you make it more difficult to trade with your neighbours, why screw up your largest export partners (46% I think). It makes absolutely no sense. If you want to trade with the EU, you have to follow their regulations anyway! So whilst Brexiters will claim there will be less regulations, there will be more.
The problem with the Brexit supporters, is that they constantly think the UK can bargain from a position of strength, when as we've seen with negotiations, we're negotiating from complete weakness. The EU can take the hit, it's only a small proportion of their trade, but to us, it's huge.
Then there's the problem of the UK itself. It's now fragmenting, and probably the end of the UK itself. Northern Ireland is in a weird place, and Scotland will have a referendum and leave the UK, and rejoin the EU. Why would anyone invest here.
Ultimately we're hitting the same problem as the U.S with Trump. Media having too much power, and politics just always being a simple divisive 2 way split, when the issues aren't that simple. Now we have Johnson, a complete idiot in control.
Now, I suspect it won't be as doom and gloom as some say. People are pragmatic when it comes to business, but the UK will have to go through some very lean and hard times in the near future.