I found Doomsday Preppers interesting but I can definitely see the heavy hand of the production team. Which is where the focus on one particular doomsday event; I'm sure that they're all just regular prepping for whatever life throws.

However, my personal take on the prepping thang (apart from what's already been said here) is the concept of community. There's only so much that you can do on your own. A community can have a range of skills and abilities and can store a whole lot more than one household. There's a reason that humans are social creatures.