Many of them are brought up with ideas taught from first grade, that their home countries are poor not because of communism/socialism, but because of colonial exploitation over centuries. These ideas are nonsensical, but this is what they are taught, and this is what their societies believe. They were also taught that Western countries are rich only because they exploited their colonies. Again, patently nonsensical ideas, but this is what they believe. The reason most come here is not out of some yearning for freedom, but because whatever quasi-religious ideologies/indoctrination they subscribe to, it is clear that American salaries are far higher than in most communist/socialist Asian countries; they hear about those salaries from those of their compatriots already here, and they see the reality of these wages from the steady stream of American TV programs and movies they watch.
VERY good analysis.