This is a disrespectful oversimplification of a very complex issue. Older people remember that Charles de Gaulle did everything that he could to keep the UK out of European politics. They remember the first referendum on remain/leave, that happened in 1975. They remember all of the exceptions, negotiations, all of the crashes. The EU is great, and I personally consider a grave mistake to leave it, but this sort of unidimensional oversimplification of complex issues is a major factor in politics polarisation.
It was incredibly stupid to pose that question as a simple majority leave/stay referendum, and then equally stupid to actually go through with it given such a narrow majority.
Certain capital owners were the ones who advocated for it, and ultimately the ones who benefited, and they manipulated the older and xenophobic.