The need of an artist to keep on growing as an artist (or just to Sell Out, to simplify things).

Sell out:  Anyone who sacrifices artistic integrity in an effort to become more successful or popular (generally in music); someone who forgets their roots. “They sound nothing alike like their previous records”, “I liked their first records, now they are popular I don’t listen to them anymore” or even “they plainly sold out” – These…