That's because they come to America for the same reason other immigrants come to our country, and can see the opportunities.
I worked with a couple of Jamaicans who were just off the boat and were helping mom and dad set up a Jamaican restaurant. Both of them asked me what in the world was wrong with American blacks. The Jamaicans had a "How long has this been going on?" attitude and couldn't believe the others didn't seize all the advantages they saw.