It's like being in mental health inpatient facility. Cognitiva Review The main indicator psychiatrists are looking for. Can the person perceive reality? Are they delusional? Is there grandeur? Of course, the purpose for admitting people to these hospitals is to give them time and treatment to come back to reality – to receive insight.
It's a scary individual that does not have insight. Yet, the narcissist is one who seems fine – until you get close to them – but has a major lack of insight. They cannot see a single fault within themselves. And they may only ultimately agree they have something to change when they see there is some advantage coming to them for appearing humble.
Now, this is dangerous; to see yourself as unequivocally superior to others is bad for everyone. You cannot be corrected when you need to be, and others are not acknowledged for the goodness and attributes they have.