I don't think you understand how good it is to be in an economic union and how bad it is to be isolated from one in terms of trade.
I don't think you understand how much bigger the rest of the world is compared to Europe. Currently, we can't agree bilateral trade deals with USA, China, Japan, Australia, New Zealand, South Korea, Brazil...

Also, the EU is a great deal more than an economic bloc.

Imagine you're a company who wants to build widgets. Caveat emptor, would you rather put your factory in a market with 1x labor and 1x consumers, or 5x labor and 5x consumers? It's not hard to see why companies are already pulling out of the UK pre-Brexit.
There's this belief that if a company fucks off, that's bad. Well it's not bad for whichever local company fills the void in the market. I don't give a fuck about companies that leave for greater profits elsewhere. Fuck them. I'm not a globalist, I'd prefer companies in this country to be owned by British people who have no intention of taking their business elsewhere because this is their home.

Latest polls have it about 60/40 Remain. That's not even close.
Do you know what the odds were for Brexit about an hour before the polls opened? Around 4/1.

That's 80/20.

Then why have any?
Because sometimes they are necessary. Why are you asking stupid questions?

It's up to them; they can have as many referenda as they want. Times change and so do opinions.
No, they can't have as many as they want. They might be able to have one a decade, but you can't keep asking the same question every three years. These aren't elections.

It seems better than the idea that the populace only ever gets one point in time to make a monumental decision at, and if they get more information and change their minds, tough shit.
I have had to endure my entire life in the EU, thanks to a referendum in the 70's. I had to wait until 3 years ago to vote to fucking leave. And the best thing is, the referendum we had in the 70's was for the EEC, not the EU. It was an economic bloc, not a political one.