I know a couple of Brits living here in the USA . . . one just got his citizenship papers last year.
I won't say that I've spoken a LOT to these folks about the reason for their move, but when the subject has come up taxes and economic opportunity seem to be their major reasons for emigration . . . though crime and government regulations were factors, as well.
(The methods one of them used
to get his own money out of Britain were eye-opening, and, I'm sure in the eyes of the Brit government, illicit.)
It all boils down to a little thing called "freedom" . . .