Rich people hording their money is far worse for the rest of the people than if they spent the money, even if it is for obscenely expensive luxury goods. That money that Sennheiser makes on the headphones is a part of its income that pays salaries, as does the margin that the dealer and distributor makes. The "waste" of paying far more than the phones are "worth" goes somewhere, it is not really wasted in the sense that it disappears and does nothing more.
I know that most audiophiles do not consider headphones as serious audio gear, but, to a growing number of people, headphones are their favored means of listening. A combination of transducer and amp that costs $55,000 in the speaker world is quite high, but, it really isn't that uncommon; why should it be any different for phones?
I would certainly like to hear them, even though I would never consider a purchase. I like their prior electrostatic offerings (HE-60 and HE-90), but find that their more recent high end offerings in dynamic phones to be wildly inconsistent (I really dislike their top of the line model). It would be interesting to see what kind of sound they pursue and whether they go for the mellower sound of their old electrostatic models or the lean, bright and hyper-analytical sound of the HD 800).