In fact, it was only after the rennaissance that the idea of an artist as a genius emerged. Before then, the artist was most often there to put into paintings what the patron described. There are still remaining documents that show how detailed the demand got, including suggestions about a "grey spot on the left flank" of a horse. It is a fairly modern idea of an artist creating something for himself or herself, for the purpose of creating art rather than creating something to show the majesty of a patron. I don't doubt that drive has often more to do with getting noticed than talent, but if you look at the great things that have come out of ambition, that is no bad thing. Look at U2, just four guys who wanted to shake up the world. Look at plenty of bands, the talent isn't what execs go for, it is the chemistry, the ability to thrill an audience, and to entertain, and the promise of greater things to come.