I find it laughable really.
British people are dissatisfied with our way of life because they have at least a smattering of knowledge of the goings on. They read the papers and vote.
I know Spain very very well. The Spanish are sick to death of the corrupt politicians, the crime rate, the illegal immigrants from North Africa, the influx of legal immigrants from Britain, Germany and Holland, the sharp rises in the cost of living, the smoking ban in bars, the drug culture...
Exactly the same reasons as the British give for their reasons to leave the UK. The difference is the majority of Brits are not aware of the reality of life abroad and think they are escaping problems.
Older people may move to Spain for the climate - but then complain about the high cost of running air conditioning in the summer, the cold solid floors in the winter, and the high cost of water.
New Zealand also has a huge drug culture.