The other answers so far have missed an important point. As with a lot of expensive art, the object itself is almost beside the point. What's really at work is status seeking. By spending a lot of money on some "art object", even ones that most of us would throw out with the trash, you demonstrate that you:
a) have lots of money
b) have the "taste" necessary to be accepted into the society that values that sort of thing
This is explained in much more detail in the book "The $12 Million Stuffed Shark".