Are you suggesting there is no comfort, food, drink, or shelter in Central/South America? Methinks you watch too much tv. Go for a visit, you might be surprised.
It's simply that the prices are too high and that there are not enough jobs. They are poor. They realize that even the poor in America eat. They are coming because they are hungry.
And you think there are enough jobs for unskilled, uneducated labor in America? Welfare to those who contribute nothing will break the entire system sooner than later. No, not okay.