familiarity can make us fear truth, if that truth is different from what we believe or want to believe.

cognitive dissonance is also fairly uncomfortable, and can cause us to reject a truth in favor of a core belief just to avoid that feeling.

also, being "wrong" about something can feel bad, so sometimes we don't face the truth in order to avoid discovering "wrong" in us and therefore avoiding that feeling.

in order to face the truth without reservation, one has to overcome a lot of evolutionary traits designed to keep us locked in step with our society and our peers, even when that truth might benefit us.