What do people travel through life with Closed minds, feeling they have it all figured out ?

I mean, at a certain point in life, it seems many people just stop letting new information change anything, they just hear or see something new , match it up with what they already believe and if it matches accept it, if it doesn't - reject it, nothing new ever gets in , has a chance of changing a person or opening up their view of the World ? Humans are flawed perception beings, yet , their flawed perceptions of the World often form a "belief system" that they defend with their very life !! Why is cognitive dissonance so difficult for humans to tolerate and most avoid, staying stuck with the same old patterns of thinking and reacting to life in the same way over and over, never advancing , progressing - we can learn a lot from each other if we give it a chance and life is always trying to teach us lessons if we stay open to it