Why do billions of people not have a Nintendo DS?
Reasons I do not (and will never) have MGS4:
1) I haven't started the series yet (I prefer going in order for this stuff).
2) The price of these type of games drop quickly, and I rarely pay full price for short(er) single player games.
3) Most importantly, my cousin has it. I can borrow it, play it, and be done with it without paying anything.