I think rich fools buy them because to them, x thousand dollars on a cable doesn't sound like that much money and they assume that if it costs more, it must be better, and they think, "By God I'm rich, and I deserve the best!"
Case in point, my dad, who is not insanely rich but can also afford thousand dollar cables if he wanted to, recently ALMOST purchased a $1k+ HDMI cable (Transparent Cable) because his installer told him it'd give him the best picture on his new Runco projector.
He didn't even think to question it, but when I was reviewing the proposal I told him he'd be absolutely nuts to spend the money on it... Once he did a bit of research, he realized the same thing, but in a different situation, he would simply have purchased the cable because someone he trusted (an installer) told him it was "the best."
So Mark, I'm with you, they exist largely because people will buy them!
