The Leave camp, during the campaign, were very strong on the idea that leaving would have economic benefits, not penalties.
When combined with the UK press use of the EU as a scapegoat for many unpopular decisions over the last 40 years, it's not surprising to see the outcome we did.
Reality will only sink in, once we've left and the outcome becomes apparent. I really wish that weren't the case and that people would look at the people pushing brexit to see they are not likely to act in the interests of the majority of the population, but I don't think that's what's happened.
EDIT: to provide one example look at https://en.wikipedia.org/wiki/Results_of_the_2016_United_Kin... The North east of England voted Leave in almost every area...