That also applies to the brain drain, and the way that Europe's best engineers and scientists try to come to the US. If they want to do cutting edge work, they as individuals have a lot better chance of it here than they do trying to create such an environment in Europe. There are too many hurdles and roadblocks in the way. Had all of those who emigrated remained behind, gotten organized, and worked hard at it they probably could have done so. If the US didn't exist in its current form, then they all would have stayed behind, and Europe would be the scientific and technological capital of the world.
But we do exist, and thousands of individuals are making self-interested decisions that they'd rather go somewhere to work that encourages what they want to do, instead of placing roadblocks in the way. And because of that, Europe is stagnating technologically.
Of course the effect doesn't apply to all of the best and brightest, but certainly does affect a significant majority. However there are two countering forces to the brain drain, namely Nationalism and Population. India is an example of a country that has been fighting against the brain drain for decades - my community is typical of Indian-origin groups in that we have a massive concentration of doctors and lawyers and other professionals. However for every immigrant that comes to the US, there are 1,000 equally qualified ones who don't, partly because of immigration controls, partly because of financial barriers, but also (especially recently) because of nationalistic pride. And a large, LARGE population, which ensures that the brain-remainder is still sizable enough to make enormous contributions. Europe has nationalism in spades, but it's population is (IIRC) actually decreasing due to lower birthrates. The magnitude of the brain drain problem affects India as much as Europe, but India's population is three times larger than all of Europe combined.
Population has its own problems of course. It's hardly a reason to envy India - in fact, I have a thesis that almost 100% of India's problems can be traced back to population pressure as the root cause (for another post. have mercy).
What is interestig about the brain drain is that it has also affected the Arab world. Mostly because due to the sponsorship of dictatorial regimes by the West for Stability's sake, the best and the brightest of Iraq, Egypt, Syria, Saudi, etc have had even more rationale to flee (those with the means, anyway). Unfortunately the Nationalism part has been dormant since Sadat and Nasser. Most Arabs are less concerned with pride than they are with survival.
Ultimately, if we are successful in Iraq, we will have to combat the brain drain as well. Already some expatriates are moving back, but things are nowehere near normal, and until the alarming rise in fundamentalism can be documented to be reversed, the smart Iraqi professionals are going to stay abroad. The way to encourage the reverse brain drain effect will be to make investment in universities and labs and other professional and industrial resources. The magnitude of that challenge is enormous.