The is actually a very good point. People are acting like it was all incredibly obvious that voting Leave was a terrible thing to do. But it wasn't obvious before the vote. At least not to the average voter.
A lot of the blame for that has to go to the media who printed anything the Leave campaign said even if it wasn't true (the £350m thing especially).
I don't think it's fair to totally blame the Leave voters for their bad decision. Besides it isn't totally clear now that it is that bad of a decision. The pound only dropped 6% (compared to 30% in 2008). And that's due to uncertainty more than anything else. It could easily go up again. In fact you can barely see the change on this graph:
http://www.xe.com/currencycharts/?from=GBP&to=USD&view=10Y
> they don't get why vast swathes of ordinary people away from London would want to leave Europe.
To me it seems like most Leavers voted Leave because of some dissatisfaction with their life (too poor), and the Leave campaign successfully convinced them that it was because of Europe and immigrants. Or they just voted the way the government didn't want them to as a protest.