[zpconn]

That may be true, but students at top schools still tend to come from more affluent backgrounds. Yes, there are "homeless to Harvard" stories out there, but generally speaking Harvard students were able to dedicate as much time as they wanted to school and extracurriculars and exploratory learning in high school because they weren't distracted by a difficult home life or forced to work just to help provide for their family.

I realize this isn't exactly what jmspring meant, but it is still true, in a certain sense, that not everyone can afford a top school. The difference is that the costs come before you even send out your applications.