As long as they APPLY for immigration LEGALLY, and OBEY ALL the LAWS, and don't expect SPECIAL TREATMENT, and DON'T COMMIT CRIMES, AND LEARN ENGLISH, and GET JOBS, and PAY THEIR TAXES (yeah, I know I'm living in a dream world), what's the big deal?
How about they do all that in their own country?
There is not an infinite amount of land, water, and living space in this country or haven't you noticed?