Re: It's a security issue.
The crowded theory holds up to a certain extent, but then check out Hong Kong, which is still--so far--one of the most free economies on Earth. I personally think culture has something to do with how receptive people are to collectivism.
One has to remember that for two hundred years, a great many Europeans who wanted more personal freedom and disliked collectivist government and oppression, left for America. Others who figured they could put up with it, compared to the pain of uprooting their families forever, stayed.
Evolution in action?