“the tendency to interpret new evidence as Confirmation of one’s existing beliefs or theories.” Wikipaedia
The human mind is abundantly able to compartmentalize and reject or disreguard inconvenient or contradictory information. Facts as they exist are either rejected or embraced in order to preserve existing prejudices rather than to increase understanding.
Inconvenient truths are typically claimed to be lies and obvious irrefutable lies are psychologically treated as truth. Religion is the most obvious example, but following closely behind are often social and political conventions.
It’s often easy for the outsider to recognize the confirmation biases of others but not their own. From the outside it appears bizarre, but from the core it provides a reference frame that provides a continuity of perspective. And so any fact that contradicts or discredits your belief is worth demonizing and denying.
People and societies pool their energies also in creating lies and attacking all who dare challenge the prejudices on which they are anchored. Facts and people who believe in facts, are in fact the trouble makers!
You tell me, is your world flat?