Many people everywhere make decision which seem/appear to others to be wrong - but they have their own reasons for doing it. Nobody on this earth ever wants to make a decision that they think will ultimately harm them. Bottom line is that people always think of the benefits which a particular decision will bring.
1. There are girls/women who wish they never ever married their partner and men who would cut off their right arm not to be married to the woman they chose. (It seemed a good idea at the time)
2. As someone once said: 'the world belongs to the brave'.
3. When it comes to the British people, they have never liked someone else telling them what to do. Remember they ruled the Empire for many years. Before the Referendum everyone else (leaders of other countries) were 'advising' the British people which way they expected them to vote. That ever works. It would have been better to say - please leave the EU, and then everyone would vote to stay. Simple as that.