megalomania vs self-interest

megalomania

noun
  • An obsession with grandiose or extravagant things or actions. 

  • A psychopathological condition characterized by delusional fantasies of wealth, power, or omnipotence. 

self-interest

noun
  • One's personal interest or advantage, especially when pursued without regard for others. 

How often have the words megalomania and self-interest occurred in a corpus of books? (source: Google Ngram Viewer )