Another 2.6 billion live in countries whose average annual income is less than Mexico’s. These nation’s earn, on average more than $2 per day, but they still earn less than the average Mexican.
Thus, 5 billion (over 70%) of the earth’s 7 billion people are so desperate to escape their poverty that emmigrating into the US or Europe has to be a great and powerful dream. These people are too desperate to give a damn about political ideology, religion or values. They live at the edge of starvation and will immigrate, if they can, simply to survive.