I think what Brexit shows is the immense and dangerous power of the human capacity for story-telling. 'Brexit' as an idea is an appeal to strong emotions - to the idea of 'sovereignty' - there is nothing wrong with that, but it appeals to a historical period that never existed.
Britain has never been an effective 'sovereign' nation, standing alone. Before 1950, we stood at the centre of a world trading empire, built on our historic maritime power.
Then after the mid-1950s, we became part of a group of countries known as the EU that later changed and expanded over time.
However in the last 500 years, we have never been a 'sovereign' state that simply stands on our own when trading with other nations.
So our future, after brexit, will unfold in what are effectively historically unchartered waters, at a time of huge global change. For the first time in our history we will have nobody to fall back on but ourselves.
'Sovereignty' is simply a collective idea. It only has meaning for a group of people - a 'nation' - if they also have the economic power to make meaningful decisions about their future. Otherwise it's just a 'dog whistle' term to encourage people to make emotional decisions based on an imagined past.
More worryingly still, we are only the 5th (or perhaps now 6th?) largest economy because we have strength in services i.e. People. This means that our GDP relies more than most on nothing more than our global reputation and our credibility. Unfortunately, there is no law that says these things can survive intact however we behave.