As we've argued before; when a country fails to solve its problems, those who are capable of leaving will do so. There's no reason for a person of reasonable wealth to stay in a nation that's making his or her life miserable. That's not rocket science; it's just simple economics.
So, when you look at a nation like France, you might assume that the ugly trifecta of high taxation, high cost of living, and radical Islam is incentivizing the departure of the financially stable. ...And you'd be right - if you placed the emphasis on radical Islam.