How can you expect to bring in millions of uneducated, non-English speaking people who have no job skills, when low-skilled jobs are leaving this country to NAFTA, CAFTA, and other free trade, people who have no ability to earn the $20,000 or so it takes for a family with several to many kids to live in the USA, people who come with no money for health insurance and can't pay our high housing costs etc and then not give them government assistance? The reason so many are on government assistance is they have children at a very young age and have low rates of legal marriage, they have no education, they don't speak our language, they work for very low wages that provide them no benefits --- obviously they can't make it on their own ---- a few can but we're not talking about a few.
Simple: End benefits, and moving away from your familiar surroundings to a place where you do not understand the language suddenly becomes a much less attractive endevour.