Minority interest Eurosceptics have done what exactly?
Billions of potential investments have been postponed.
As they were immediately BEFORE joining the EU - the people thwarting a clean fast exit are to blame for this.
Transaction cost for businesses raised soon to be followed by price increases.
When Spain / Germany / Italy ... joined the EURO prices were increased by unscrupulous retailers, they will use any excuse to hike prices and make the public pay more.
Pound crashing to 1.20 against the dollar reducing UK's purchasing power on the world stage.
Which will make UK companies more profitable when dealing with foreign competitors this is a good thing for the UK. Trump is trying to force the FED to devalue the dollar, we get it for free with brexit.
Existing industries leaving the UK.
Industry - UK ???
Future businesses thinking of locating in the UK changing plans. Unless ofcourse you are Amazon, Google or FB and simply don't want to pay any tax and employ low end low skill personnel.
So companies leaving the UK due to brexit is a bad thing (your previous point) and companies coming to the UK due to brexit is a bad thing!
What have Brexiteers delivered thus far? Who believes in their promises to deliver global bi-lateral deals that's going to make us better than what we have now?
Companies always find ways to make money no matter what regulations apply, any who cant adapt will fail and new more competitive ones will take their place that is the nature of business.
Change is necessary and good, don't be afraid of it!
Undermine national interest indeed! LOL