is immigration a social problem

Yes and no, depends on how you look at it.
Well, some people believe that when people emigrate to another country, they cut down some of the resources from their home country, whether it being financial resources, human resources or something else. And some even believe that those who emigrate have "betrayed" their homeland in some way. Thus cause some sour feelings, or even prejudice. Or there are those who are simpley envious because they blindly believe life abroad is much better than their own. And some of these people might be willing to do anything they can to emigrate which could be dangerous or harmful to the society.
But on the other hand, there are those who think that there shouldn't be borders and boundaries between countries. And you are contributing to the same world no matter where you live. To these people, immigration is not a socila problem, but rather a way of life.

移民是一个社会问题吗?