Yes, people should have self-determination, and there's lots freedom in a state of nature as they say. (Except when there aren't good choices available...)
But, then people discover that larger societies and cooperation come with benefits. Of course, the devil is in the details as they say, but Britain was getting a great deal out of its membership in the EU. I understand that not everybody benefits equally, but on the whole it's been a positive for GB.
There was lots of misinformation about the Brexit. Those leaders who campaigned for it are now mumbling a different tune as to the huge benefits that Brits immediately (or long-term) would enjoy after the exit. One issue was immigration and free travel within the union, but illegal immigration wasn't GB's own problem; all the members had that. Also, GB wasn't a signatory of the Schengen Agreement (free, no passport travel among members). Plus, GB had own currency, etc.
Many Brits didn't fully understand the details of what the EU membership entailed. I'm not saying they didn't have the right to say they want out, but I also think the vote was based on misinformation and on many levels of dissatisfaction with own economic status, against globalization, against the economic elites, immigration and fear of refugees, the struggling middle, lower classes, etc.
As for important revisions, many constitutions require big majorities, on the theory that 50% +1 vote is a slim margin that can change from day to day. In the US, 2/3 Congress (both chambers: House-Senate) must vote 2/3 to amend the constitution, plus 3/4 of states needed.............
This Brexit triggered lots of discussion about Greece. I know we had a long and heated discussion last year on the topic, but let me reiterate my view that Greece outside the EU would be far worse. The country has demonstrated incompetence at every turn, and when the going was good it was not because Greece was isolated and left to its own devices. Before you start cursing at me, just think of the systems and projects Greece has undertaken without foreign direction...... A few things come to my mind... tourism, the Olympics, the (gasp) Super League, elections, pollution, etc, etc....
I'm not in favor of foreign tutelage for Greece, because foreigners want to protect and advance their own interests. But, sometimes, irresponsible people need a good structure and supervision to recover. Greece needs to be more European to solve its problems. The terms are very harsh now, I think excessive, but if Greece is to change for the better, it's through the EU. Hopefully, there will be a "haircut" of the debt but Greece by-and-large is still steeped in corruption and inefficiency while blaming others for its mismanagement.
On a side note, there are lots of media talking about ..20 years since the death of Andreas. Well, he was in a unique position to do great things for his country but did great harm by setting Greece on a disastrous path 30 years in the making.
It could be said that Greeks themselves were always so fractious and warring that were not able to cooperate ever since the 1821 Revolution, they looked to the superpowers for leadership. Yes, the first Greek parties were... The British, French, Russian... It's like when the Greek teams were hiring foreign refs for their football games for the derbies.... No?
If the European leadership reads the Brexit as a warning sign that the middle classes should be the main beneficiaries of economic policies, Europe will emerge stronger. It may also benefit Greece in that the national debt should not be paid at the expense of killing the debtor. But, no matter what, Greece has to change its practices and they way it does business, and I believe it can be best done within the EU, and under supervision. I know this injures national pride, but...
_____
and now something fun: