I don't want to open a can of worms again, but the picture is not a photograph. It is a composite made of a photograph. Gursky himself does not claim his pictures being photographs. Gursky is not making pictures, nice to look at, but ideas and concepts you can look at. Some may consider them nice to look at or at least interesting.These ideas and concepts are considered being art. You will have to know and appreciate this to appreciate his pictures. As far as I know, he isn't even making all of the pictures entirely himself.
It's not Gursky making the money but the owner of the picture/gallery who is making the money (though it may not have been cheap in the first place I suppose. He addressing a certain audience by making his pictures large).
Ulrich