I think its fairly easy to make a case of why the EU is a bad institution. I have made so here and other places. I think people are blinded by the idea of the EU but ignore the actual EU. Can anybody deny that the EU has shown horrible management in everything related to economics? We have a Great Depression level crisis and now a horrible slow recovery. 90% of this hole crisis could have been avoid if the EU and specially EMU were such horribly setup institutions. The EU is not really democratic either, when it should be the most democratic. It should improve on the state of institutional democracy, while in reality its a very clear step back. Take a look at Swiss Federalism and Direct Democracy, its a much better set up for a system but many of the ideas are nowhere to be found in the EU.
Britain has economic problems right now because a lot is changing, but I see no reason that the long term growth should be negatively impacted by this. In the long term I think it can be a net positive. It all depends on how Britain will operate going forward.
Only 37% of the population was needed for this, but this is because the UK voters had been apathetic about the opportunity to reform the voting system.
So how can they claim to be disappointed by the EU adopting the same polities?
The UK has a reason for their bad system. They have a very gradualist history. Compare it to France, where we are talking about the Republic 5 right now.
If we are doing a project for European Unity is should actually be better then everything else. It should be better then Switzerland, not worse then the UK.
Of course many people voted because they want to "close the borders" but: 1) This doesn't invalidate the sovereignity argument. 2) The protectionism/anti-immigration stance is a reaction to the existing politics, not the cause. And it's something we currently see all over Europe.
There are more valid arguments for leaving the EU, but I think the argument for democracy is the most important one. Saying there are no good arguments to leave is dishonest or ignorant.
What's the answer? It is something you should consider, because while you can argue it isn't actually true in this case or that, certainly you have to admit it is theoretically possible. It seems like a failure mode one should anticipate and be prepared for. (I must admit, I have no good answers, and so am not prepared.)
It's pointless at best, actively harmful at worst, to compare the voters vs the non voters in an attempt to make the result seem undemocratic. The non voters abandoned their ability to influence this issue; if they had wanted to participate, they had plenty of opportunity to do so.
[1] https://en.wikipedia.org/wiki/United_Kingdom_European_Commun...
[2] https://en.wikipedia.org/wiki/Demography_of_the_United_Kingd...
-They are stupid.
-They are xenophobic racists (over 50% of the population!).
-Trump welcomes the Brexit, so being pro-leave is stupid.
-Old people vote "leave" since they don't have to face the consequences as long as the young people, and old people have no clue.
-"Leave" votes come mainly from E.U. subsidized areas, thus they bite the hand that feeds them.
-Pro-leave doesn't even know what the E.U. is.
I have read a lot of insults regarding either position, but the attribution of stupidity comes almost always from the "Remain" camp. Which comes close to saying: there are no reasons to vote for leave, so they must be stupid. How stupid.