No, not wealthier than average, at least looking at all the expats I've met. It is not about the money, at least for me. I refer to the feeling of insecurity you get when your studies or contract are over, you don't yet have a new one, and you might have to take all your belongings and move out of a country where you lived for years, just because you can't renew your visa. As an EU citizen outside my home country but still in the EU, I don't have that. Many PhDs from Turkey I have met ended up like that. You don't want to even risk that kind of situation.

Also in the past people moved abroad for work. Now it's easier, from a bureaucratic and economic perspective. Doesn't mean everyone WANTS to move: most people are perfectly happy living in their hometown, or at least same country, as long as you can make a living there[1]. But this should not surprise anyone, it's not that most refugees would leave their countries if they could find a job and security in their homeland .

[1] btw, I have no stats but the feeling is that most internal migration in Europe is from the poorest countries and/or social classes to the richest countries. Which, again, makes a lot of sense...