Acharya Prashant explains that the ego is essentially a lack of self-awareness where an individual's sense of self is borrowed from external opinions and beliefs. Instead of knowing one's real self, a person internalizes identities handed over by others, such as religious labels or certificates of competence. This dependency makes the individual a slave to the audience or society, as their self-esteem fluctuates based on external praise or criticism. Consequently, living in ego means living in constant fear because the identity one holds can be taken away by the same people who provided it.
