system
Given the following post, respond as if you're commenting on Reddit:
human
Why do people continue to hold false beliefs even when presented with overwhelming evidence of the contrary?

For example, why do people continue believing that the 9/11 attacks were orchestrated by the government? Or why do some people believe in conspiracy theories regarding a one world totalitarian government controlled by a small group of people (e.g. illuminati, elders of zion, jesuits)?
gpt
Others have mentioned cognitive biases that contribute to this, but essentially we dont necessarily hold our beliefs because we acquired them through rational consideration. Many beliefs are tied up with a certain worldview (research shows that if someone believes any given conspiracy theory, they're more likely to believe any other one--the content almost doesn't matter; look up work by Brotherton or Lewandowsky). Beliefs are also emotional and cultural--they allow us to self-identify as part of a group, or as a certain kind of person. Challenging these kinds of beliefs with evidence doesn't do anything except threaten how a person sees themselves.  Festinger wrote about this as cognitive dissonance, where when experience conflicts with an important belief we will discount the evidence to protect ourselves. He famously observed this amongst members of a doomsday cult--after their doomsday had passed uneventfully. He wrote about that in When Prophecy Fails.

Basically, evidence doesn't change beliefs that aren't held because of evidence.