In his new book, "No B.S. Business Success in the New Economy," Dan S. Kennedy makes the distinction between people who are in it for the art itself and those who want to be creative in business.
The artist starts with a blank page or canvas; the creative entrepreneur starts with something like a perceived need and maybe an established way of doing things that he or she tries to improve.
The 'pure' artist can be guided by intuition and break totally new ground. If supported by a grant, a patron (who could be a spouse or partner), or some other source of income, this type of artist need not care whether the public accepts what he or she offers.
The artist, writer, or inventor who wants to make money with their art, however, has to be guided at least in part by the marketplace. "Build it and they will come" is a romantic notion, very appealing, but not reliable.
This split probably is what many of us find the most difficult aspect of creativity to deal with. Navigating between what you want to do artistically and what the world is ready to pay for isn't easy.
It's interesting but not surprising that the kinds of writing that give you the least ultimate control over your work pay the best. Scriptwriters have no power over what happens to their work once they hand it over. A tender love story can be turned into a torture-porn thriller if the producer feels like it ("Hey I have an idea--instead of wanting to marry the girl, he wants to imprison her in his cellar!") But they pay you well for the right to do that to your material. The same is true for top-level copywriters.People who write for the stage, on the other hand, can insist that nothing be changed--but unless they happen to have a hit on Broadway or the West End, they won't see all that much return for their labors, either. That also is true for most novelists (again allowing or the occasional Grisham or Rowling as the exceptions). And as for poets...never mind.
It's not that one kind of creativity is right and the other is wrong; it's just important to know which is which and to go into whichever you choose with your eyes open. Going into either one with false expectations is a sure prescription for unhappiness.