When things are not looking rosy, it always easier to say no rather than yes we'll try. Blame someone else for your trouble, which is what Brexit philosophy is based on. And put up the shutters.
Pretty similar to all populist movements flourishing around the world at the moment - Trump and Sanders in the US are great examples but there are many more in many countries.
Say no, reject whatever the "establishment" is putting forward, blame the "system", but have no realistic plan whatsoever to implement should you end up in power.
UK folks should remember that at the time they joined the EU, they still had some remnants of an empire that reached beyond their borders. That is no longer the case. If they leave the EU now, they will find themselves on their own. Isolated. Do they realise the implications of such a move? Most probably not. Populist propaganda is negative and short termist in essence.
Now, will the rest of the EU miss the UK? The answer to that question is not so clear cut...