Well, the deal is, according to one of the players in my game who is in the military, that a bunch of military folks who play RPGs in my town, spend their money on RPG books.
When they have to go to their next station, leave, etc., they need the extra cash, so end up selling their "extra" RPG books. He also says that many of the military here have no real friends or family so just splurge on books, but end up buying more than they really need or can actually afford. They find out that they have to pay for necessities, like food, and sell the stuff back.