Denial of reality is one of the most self-destructive behaviors a person or people can engage in.
The only way to most effectively navigate the world, and affect change in it, is to confront external and internal truths in as sober and objective a way as possible.
Without this, you're fighting straw-men, dogma, fantasy and figments of your imagination. You're creating inherent tensions for no other reason than your own willful ignorance and stubbornness.
This leads to unhappy relationships, broken families, failed states, civil wars and world wars.