So it isn't because people find entertainment in violence and competition?
Anytime something says Battlefield or Call of Duty people/kids are going to have a boner for it and stay out for midnight releases even if a commercial or preview has not been shown. If I were in charge of those companies I'd really like to promote a new Battlefield/COD without showing any gameplay footage. I would just make "Games" where all you do is look at the main menu.
Unless I'm mistaken, I see what you're saying. IMO a lot of people seem to buy the games just because it's "A NEW COD" or "A NEW BF!!!11"