Why does Bill O'Reilly constantly talk about ratings on his show?

Almost everyday, he compares his ratings to "liberal" networks such as MSNBC and CNBC. He brags about how his show is the most watched show in cable news and "liberal" shows such as Countdown with Keith Olberman have low ratings. Do you think by him bragging about his ratings is a way of saying he is right about the topics he discuss and he has the ratings to prove it? I mean seriously, what do ratings have to do with facts? Having a high rated show doesn't necessarily mean he is right about everything he talks about. What are your thoughts?