Lots of people did know what was going to happen, though. Lots of people tried to warn about what was going to happen. Some people chose to ignore the warnings and believe the nonsense that they saw on the side of a bus instead.
I do absolutely accept that some of the electorate lacked the intelligence and critical thinking skills to be able to analyse the arguments on either side, and I don't blame them for that. Those people will inevitably be susceptible to soundbites and it isn't their fault.
However, I believe that many people who did have the capability to make an informed and considered decision chose instead to bury their heads in the sand and ignore the warnings because they preferred the other narrative. Either they couldn't be bothered to engage and think about the issues at all, or wishful thinking caused them to close their minds to the opposite point of view.
The question shouldn't ever have been put to the electorate in my view, and I blame Cameron for this more than I blame an ignorant and disengaged electorate. We are where we are, now, and we all have to suffer the consequences of the terrible decisions that people made at that time. But I think it's natural for people to feel anger towards the Brexit voters who helped to create the mess that we're now in... if they had educated themselves a bit more before the referendum, or stayed at home on polling day if they couldn't be arsed to educate themselves, then we wouldn't be in the state that we're in now.
I think it's very hard for the younger generation. My dd is now an adult but she was a child when the referendum happened, so she didn't have the opportunity to vote on the issue. It's only now that she is starting to fully understand what she has lost as a result of the poor decisions of the generations above her. It feels very unfair.