I live in the UK, and I have mixed feelings about Brexit, most immediately dismay, because I'd prefer a world with no borders, not more than we have now; but also a feeling of anticipation, because finally something has happened that has the potential to shake up the status quo in Europe. After what the EU did to the Greeks it does feel good that the super-state project is now on the back foot.
I'll warn you now, this'll be a long post, and I'm going to go off on a couple tangents, but it's all relevant from where I'm sitting.
I'm not a leftist, but the outrage over how the current globalised order has immiserated, and is immiserating billions of people, which has propelled Europe's new leftist movements to prominence (Syriza, Podemos, Corbyn etc) is something that I feel too, and so I do sympathise with these movements. The problem for them is, as we witnessed with Greece, that the nation state is no longer sovereign, especially in Europe. So even the election of a radical leftist government (something which would ordinarily not be allowed to happen, but which couldn't be stopped because so many people were so angry at the establishment) was defeated by supranational, supra-state captialism. Britain leaving the EU is about the biggest 'fuck you' that my corner of the world could have given to all of that.
However it won't fix anything that people want it to fix, no one will get more sovereignty, power or freedom out of this. It's not going to fix liberal democratic capitalism, which is in a long term crisis - in western (and now some eastern) economies, jobs are being automated and outsourced overseas, so demand is slack and people are pissed because we still have this ridiculous notion ingrained in our culture and socio-economic structures - that to live you must work, and there is less and less work. Capitalism's answer so far has just been to outsource, expand certain sectors like the service, tech and finance sectors, but it can't go on forever - unemployment and casualised work is incredibly high across much of Europe and no one has any idea of how to deal with it. Either automation or climate change will bring things to a head, when enough people are simply not able to make a living from work,and it may be in our lifetimes.
On the other hand, for a great many people Brexit isn't about saying 'fuck you' to supranational authoritarian capitalism. It's about simple xenophobia, 'sending them (people who aren't white or don't speak with a British accent) back', having an excuse to be openly racist and unashamed. I'm not into morality, so maybe 'unashamed' isn't the best word, but racism is something I can't abide. Too many of the people I care about aren't white, and racism is based on essentialism, the denial of empathy and exclusion of those who are different,outsiders. It disgusts me, and thanks to this referendum non-whites and immigrants are now facing an emboldened tide of racist abuse and attacks. Even the police have said the referendum is responsible for Britain's 'worst rise in recorded hate crime'*. I'm worried that regardless of whether Trump wins or loses the US presidential election, when it's over we'll see something similar in the US, when either the racists are emboldened by his victory or enraged by his defeat (which he'll obviously claim was rigged...which it is, but not against him specifically).
If I'm honest, the most infuriating part of the Brexit story is how unoriginal it is. It's just the wealthy elites playing power games with each other and screwing over everyone else in the process, much like WW1, just with a lot less dead bodies.
This whole thing began because (now former) Prime Minister David Cameron was afraid he wasn't going to win the last election, so he put the referendum in his manifesto to appeal to the Conservative party's support base, and keep them from defecting to UKIP. All the polls suggested that no party would win outright, so he anticipated having to go into coalition with the Liberal Democrats again, who would make him repudiate that particular manifesto pledge. Only that didn't happen, the Conservatives won outright, and from then on it became a personal power struggle between a couple of private school boys who'd been in the same exclusive dining club at Oxford University (look up the Bullingdon Club, it's a perfect example of the British upper classes' excess and exclusivity), and were then both leaders in the Conservative party. The referendum campaign was full of lies, false promises (shocker!) and toxic anti-migrant/'Make Britain Great Again!' rhetoric. Now there's a recession coming, and everyone who's not wealthy is basically fucked, but at least something's broken the inertia and stirred up some confusion in the institutions :)
I have many more thoughts on this shitshow, but that's where I'll leave it at for now, don't want to pop a vein.