Well, a lot of countries aren't worth leaving. Taking my home of the UK as an example, Wikipedia lists 19 countries with higher GDP per capita, but if I don't want to learn a new language, overcome bureaucratic obstacles and leave my family behind, there is nowhere to go and this criteria describes almost everybody who gets an education here, even the smart ones. Romania is #53 on the list and their EU membership means they can emigrate easily.

I'm pretty sure there is a mass exodus of British Nurses to Australia.. And for tech or finance, America is the dream...