The act of deceiving oneself or being deceived by one's own mind.

आत्म-विभ्रम

English Usage: His self deceit led him to believe he was successful when he was not.

Hindi Usage: उसका आत्म-विभ्रम उसे यह विश्वास दिलाने लगा कि वह सफल है जब कि वह नहीं था।