People believe those things because they don't or can't take on the responsibility of discerning truth from within.  A man born with a dick won't conclude he's a cat-dog in isolation.  

The cacophony is loud & exciting, it's not impossible to tune out, but some folks go through life without ever trying.  They never form their own core identity, so they very easily believe they may be a cat-dog, if the cacophony serves them such a message