Economist Tyler Cowen wonders, and his readers speculate in the comments thread. An excerpt as to what's tickling his economist bone on this question:
Have you noticed that storage is really, really cheap these days? Have you studied the durable goods monopoly problem? Once you've accumulated a stock of durable material, at some point you will sell off successive units very very cheaply. Have you noticed that costs of electronic reproduction—call it marginal cost—are really, really low these days? Have you noticed there is a massive stock of accumulated pornographic images?
……… Call me clueless, as I have very little direct knowledge of pornography. But I don't understand why buyers demand such a regular flow of material. Why don't they just buy a single dense disc of images and keep themselves, um…busy…for many years? I believe also that fetishes are fairly stable and predictable. You don't need to see "the new porn" to know what you will want to get off on.
As I observe the sector, buyers cough up new money all the time, and they buy relatively small units of output, and at relatively high prices.
Have at it, porn fiends!