Self-deception (noun)

The act of deceiving oneself by believing in something that is not true or by ignoring facts.

Origin:

Combination of self and deception, meaning the act of deceiving oneself.

Examples:

1. He engaged in self-deception to avoid dealing with the truth.
2. She was guilty of self-deception, pretending that everything was okay when it was not.
3. He was a victim of self-deception, believing that he could succeed despite the odds.
4. The self-deception she engaged in made it difficult for her to make progress.
5. The self-deception he engaged in led him to make a poor decision.