Well okay, mass market books are cheaper than mass market games. But mass market cars are more expensive, and plates somewhere between games and books in the main. And most people wait around for a car they want to become available used, because they're so expensive. Surely its a continuum, where people are more enticed by second hand items the more expensive the original is.
Because books are significantly cheaper. Most people wouldn't bother waiting around for a used copy of a book they wanted, they'd just buy it for eight quid or whatever, who cares? How many second hand book shops do you see these days?
Yes it is. Books are sold in shops on the high street. I can buy them online. I can rent them (from my library). They're even electronic media these days, as e-books. Granted, they're not interactive as such, unless you include those old choose-your-own-adventure books. Publishers publish books, and authors develop them. Seems a pretty good analogy to me, no?
Finally the video game business in not analogous to cars, plates, books or anything else.
FWIW there are two second hand bookstores between me and the local station, and I think three charity shops which stock books. Only one new bookstore, two if you count the Smiths in the station.