As having worked in tech in another country, and moved to the US to work in tech, it's 100% to do with the US understanding the value of the engineers. Among my other expat acquaintances, it's not just my old country, either.
A couple of good engineers can pull off the next google, instagram, Facebook etc. Folks in the US know this and harness that power. Other countries see an computer engineering degree like an accounting degree. Until other countries clue in, the US will continue to be a power house.