The short answer to that is bcuz humans (not all) like to be known, praised, and remembered for their identity.
Long one: In modern world standards - successful life style - fame is a major indicator of success. Famous people become wealthy and known which increases their worth. The feeling of being wanted (in demand, loved, longed for...) raises self-esteem more than anything else. This feeling not only gives a boost in confidence, it sparks the trait of arrogance and pride also. Let me be frank, arrogance and pride are very delightful to human heart, especially when it is totally centered to self aggrandizement.