By charging such high prices, you're standing in the way of social progress, so I'm justified in ripping you off. At least that's what I believe as I walk out your door with those texts under my coat. Another motivation for book theft that booksellers will understand as quickly as they deplore it is intellectual compulsion. I want that book by Kant or Hegel or Marshall McLuhan because it's worth studying. It's so easy to drop it in my shopping bag.
Successful theft depends on three steps.
First, I must target the items that I want to steal, what they are and where they are located in your store. Secondly, I must conceal those items so that neither you nor a customer will suspect me of theft. Thirdly, I must exit the store without being stopped, questioned, assaulted or arrested. Once I'm outside and a short distance from the store, I'm safe. What the police might be interested to learn about the old guy is that his apartment is crammed with one of the better private collections of media history, all of it stolen.