Cancer surgery is an extremely important decision, directly affecting many people's lives.
What happened with Brexit was a analogous a bunch of salesmen on TV saying "that mysterious ache you have, don't listen to doctors who say it's fine, call our surgical team today! It's cancer! We can fix this quickly and you'll be back to your old self within a week!" for two decades, then the country agreeing, going to surgery, and waking up to find they'd had half their liver removed, the post-surgical biopsy results said it was fine and not cancerous at all, it took 6 months to recover and they could never drink alcohol again. And the ache was still there.
If it had been an honest "we know it will cost X, we are willing to spend this because otherwise what is the point of money", that would have been totally fair.
Instead, problems that weren't caused by the EU were blamed on it for decades, while the benefits of membership were treated as the natural state of the world to the extent that talk of losing them was equated with "being punished".
Not all referenda that might win a "yes" vote are sensible to propose.
> The referendum was originally conceived by David Cameron as a means to defeat the anti-EU faction within his own party by having it fail.
After that, another issue is that the leave campaign was heavily based on lies and misleading the British voters.
Couple that with a extreme form of policy lock-in / hysteresis: you need just to form a small margin in a majority at a single point of time. After that point of time, the popular opinion doesn't matter anymore because getting back to EU isn't as easy as leaving. So the misinformation campaign need to work just once. By the time voters realize what happened, it's too late.
This situation is a critical failure of democracy. Not just direct democracy, representative democracy can't work in a post-truth world either.
This is very different to age sniffing here. Age sniffing is not being queried via public votum - lobbyists push it through without any resistance. It's amazing how this works.
This whole argument is why we do not have more direct democracy. The people in power and people who benefit from the status quo do not want the hoi polloi taking the "wrong" decisions. We might end up nationalising things or taxing big business effectively or all sorts of terrible things. Better to just give people the illusion of choice by letting them choose between two "neo-liberal" parties.