Who could blame them? The US is an inhospitable place for immigrants. People won't give them a chance to assimilate. They'll be suspicious of them from the start (like some of the comments here), they give them a hard-time if they don't assimilate right away and won't go half-way to be friends with them.
Compared to where? China? India? I think immigrants assimilate just fine into the United States. Assimilation is not easy anywhere. The United States isn't perfect, but plenty of immigrants are living great lives.
