Why do some Americans don't care about you if you can't bring in money to the economy?

I notice that some Americans love Illegal Immigrants(Mexicans) because they are hard working, but let a Haitian or a African, Somalian, etc. come to America or attempt to do so...and it's like "We don't want you here in this country, Go back, keep them out!" I found out it's not really about a skin color, it's really about if you don't have nothing to contribute to American society. Americans don't want you coming into the country point blank. Is this being cold hearted or is this just about the almighty dollar and not wanting to pay more taxes to take care of more people who can't contribute to America? Which one is it? Or....Is it both reasons?