Humans are naturally selfish, we are born that way, if we weren't most of us would not survive infancy. The ego is our survival, and it is also why it is so difficult to hear the words of another without inserting our judgment onto what they have said, whether their words line up with our beliefs or not. When someone says something that doesn't match what's in our heads, we have the opportunity to practice hearing. Hearing is not the same as agreeing or becoming indoctrinated, unless we have very weak boundaries.