It's very easy to make very good money in the US, compared to practically anywhere else in the world. Mundane corporate IC paper-pushers with no discernible talent can make up to six figures - which is salary restricted to mid- and high-level management in most other industrialized countries.

What's more, taxes in the US are lower than in most other industrialized countries. In result, an (non-software) engineer in the US easily makes $5-7k after taxes, whereas in Europe we gets maybe half of that (not to mention that practically everything is more expensive in Europe). That extra money is crucial for setting up a comfortable family living. Not to mention he also gets pretty good health care coverage from his job, often better than what the "free" medical system in Europe provides.