Why Do Some People Close Their Eyes To The Truth?

They call it cognitive dissonance. It’s hard for them to accept things that contradict what they have been taught by the educational system, media, etc. So they refuse to accept it even when evidence is starting to present itself. I’ve had conversations with younger people who will drop the conversation when you give them a bit of evidence that contradicts their belief and they’ll either change the subject or clam up not even wanting to hear a few words about it.