The culture I found in Sweden for instance is one that is much better for the employees than the fast-paced top-gun style of programming expected in the US. Sure my peak will probably be 60k, but that 60k will also come with a much better social quality of life. That's the problem with the US that would risk brain drain in my opinion. Money attracts people, but treating them well will keep them and the US is starting to fall away from treating its workers well.
Edit: just think about this. Most Americans talk about how they have so much work to do they don't get vacation. Well in Europe you usually get your 2 weeks and in many countries you get 4 contiguous weeks without question. Couple that with better healthcare options, and yeah the US is not looking so great.