We have too many AMERICAN CITIZENS like you described. They will become more and more marginalized and more and more desperate eventually.
The children of Mexican immigrants actually tend to do less well than do their immigrant parents. The parents may be hardworking, but their children all too often are worthless -- too many of their sons become gangbangers and to many of their daughters become welfare mamasitas spawning offspring by their gangbanger boyfriends.
It isn't feasible with our very high costs of living and very high standard of living to think that millions of third world people with no education, no language ability, no job skills can make it on their own and be self-reliant here. A very few can.
You are making too much sense. The quality of immigrants to this country from around the world has deteriorated, not only from Mexico but from India, China, as well.