from a pure usage standpoint I would say that the immigrants are the ones maximizing the system!
they come here, work and save as much as possible run up a large amount of debt then leave, go back to their country and live in comfort. They come here wth nothing, when the process is over the own land and big homes in their native countries.
That mexican that you see cutting your lawn, as we approach retirement, he will live in greater comfort than you..chances are that he will own more land and have a bigger house that is paid off.