"the chief measure of success is the size of the audience".
I could be tempted to take that to a more cynical level, and say that sometimes it seems that the measure of success is the number of people who are aware of the entertainer's notoriety. In other words, the only point is becoming a "celebrity".
Cher, for one, at least has the self-awareness to say, "I'm not a singer, I'm an entertainer".