"I'm pretty sure I could have done a better painting when I was in the fifth grade, on my first try."
Whether you could have done it on your first try or not, remains to be seen. I have no doubt that you could have done something equally good after a few months of practice. The quality of the work, however, doesn't have as much to do with the multi-million price tag as you would imagine.
Beyond the physical artwork, there is the motivation behind creating it, the method of creation, and the ability to spawn discussion are all much more important than the work itself as far as price goes.
Celebrity name goes a long way into selling art works as well. Take Jeff Bridges star of Seabiscuit. He is a photographer. I haven't seen many of his photos, but in a Photo.net disscussion, some people seem to like his photos while others not so much. The point is that as a movie star, it is much easier for him to get a deal to publish a book, than it would be for you or I. It doesn't matter how technially profficient we are or how beautiful the photos are. We don't generate the buzz that a movie star does.
The point I am trying to make, is that the quality of the work is not so important as people seem to believe. In many cases they are right when they say they could do just as good on their first try. What they can't do is generate discussion, explain why they made the work, or be famous enough for people to care about it.