Part of my point is that unanimity (amongst the people) in democracy is pretty much unheard of. So Brexit was not done by everyone. Realistically it wasn't even done by a majority of the population. All the others are in for the ride despite being against it.
Democracy may be the best system we've got now but it sure sucks sometimes. It's why it's called the dictatorship of the majority, and many countries are democratic and yet have very little protections for the different minorities, particularly the ones who have no chance of becoming a majority anytime soon.
The other part of the point is that most times people don't suffer from some of their decisions despite taking credit for any when it suits them. Similar to sport fans where when their team wins "we won", and when it loses "they lost".
Public support of the Iraq war went hand in hand with the UN both finding WMDs and approving action[0].
The lies about Brexit are pretty infamous: from £350m/week for the NHS to stoking immigration fears and the fabrication of EU powers.
While it's disappointing that people are convinced by these types of lies, I'm not sure they're fully to blame; or that it does much good to do so. The bigger question is how do you combat these lies. The ones that seem to tickle the part of the brain where factual arguments don't seem to have much sway.
An example of this that I have heard many times is that of Blair and Iraq.
However now the situation is more interesting as Brexit was done to themselves, not others (though that does not make any suffering ok).