It is quite possible that people with higher earning potentials tend also to be accepted by elite schools, instead of elite schools adding "value" to these people.
This may be the premise of the book "It's the Student, Not the College", discussed in an old thread
here.
Also the book "Where You Go is not Who You'll Be", discussed in an old thread
here.
The research tome, "How College Affects Students" mentioned in an old post
here may also be of interest. The defining characteristic may be
internal locus of control.