Creativity and the expectation of payment

They're not very strongly related.  Latest example from Slate's series on Free to Be You and Me.  Read the whole thing, but have a quote:

Dan Greenburg marvels today that while the movie he went off to film in Martha’s Vineyard—the one he thought would make his career—was a total flop, the two poems he dashed off one afternoon on set have resulted in steady royalty checks every year since.