Bernie Sanders never made much sense. He may have had appealing ideas about some of the wrongs of American society, but the rational numbers of his proposals never added up, and you didn't need to be an economist to know it. Yet he racked up, what, 12 million votes? Quite a number.
Trump doesn't make any rational sense, not if you keep in mind the extreme complexity of running the United States and being the single top figure in international politics. Yet here he is, the presumptive nominee of the Republican party, which, like it or not, is one of the most important political parties in the world and in history, along with the Democrats. Observed rationally, there's no contest between Trump and Hillary Clinton. Yet given the numbers of votes cast, clearly there is.
The idea of Brexit is ridiculous. There's more or less total unanimity among economists that the UK leaving the EU would be a bad idea, one no sensible person would entertain for more than 3-4 minutes if it was early morning and they were still a bit groggy. Yet so far as we know, the voters of Britain are about to vote to leave, just next week, a prospect the polls are now giving more than an even chance of happening. (UK polls, as in other countries, can be seriously wrong).
Most people don't vote because of the numbers. Not on the Left, not on the Right. They vote mostly for emotional reasons of one sort or the other. That's in the venerable and functional democracies, of which the UK and USA are the two sizable oldest. So they can't be swayed by rational arguments, either. Marketing 101 will teach you that, and if it doesn't, go to sales 101.
All of which is generally forgotten when people discuss the Arab-Israeli conflict. Then, suddenly, the calm and rational outsiders look at the warring locals, tut-tut, and admonish them to be reasonable and rational just as they, the observers, are; and to make calm and rational decisions, since those are the only kind possible. Whenever we, the locals, try pointing out that the conflict we're embroiled in isn't about rational matters at all, it's about other and much more powerful issues, the observers roll their eyes and proclaim that we don't understand how reality works.