bitter pill vs success

bitter pill

noun
  • Used other than figuratively or idiomatically: see bitter, pill. 

success

noun
  • The achievement of one's aim or goal. 

  • Financial profitability. 

  • One who, or that which, achieves assumed goals. 

  • The fact of getting or achieving wealth, respect, or fame. 

How often have the words bitter pill and success occurred in a corpus of books? (source: Google Ngram Viewer )