Dinahmo
Dickens I remember the last time there were threats of tax hikes and the right wing press said that people would leave the country. It didn't happen. Some people tried but soon moved back to the UK because their families were unhappy but most people preferrred to stay because of schools and lifestyle.
There were various reasons given as to why the business-owning rich didn't leave, and family, schools and lifestyle was one of them. They have a life outside of their enterprise, and if they move to a country where they can employ workers on a low-wage, they get the culture that goes with it which is not always to their liking, nor their families'.
Of course, very large businesses can run without the owner in-situ, but that also presents problems. And then there are conglomerates participating in different markets, etc.
Life in the UK for the very wealthy is, in fact, quite pleasant, and that's why they mostly stay I think.