I understand what you are trying to say. But the author does point out that having a quiet ego is associated with many positive life outcomes. He links to this paper - http://selfdeterminationtheory.org/SDT/documents/2003_BrownR...

I haven't gone through the referenced paper but I think it should answer your question to an extent. Also, I feel that the author has been quite diligent has linked to multiple papers to back up his points.