It isn't just that they tend to consume more in government resources than they pay in taxes. They hurt us in other ways. As I drive through my little town most days, you see illegal immigrants mowing the lawn, most of them working hard and doing a good job.
But, they cause two bad things to happen. One, they do the job too cheap for an American to do it, so the poor, dumb bastard on the bottom of the food chain doesn't get a job, and he gets welfare, food stamps, becomes a drunk, etc.
Second of all, because all the Americans don't get off their fat asses and do the manual labor themselves, they get fat, get high blood pressure, diabetes, and clog their veins with cholesterol, driving up health care costs, and lowering productivity.
They are fucking us over in ways we never even considered until now.