Ha, you may be underestimating your survival instinct. Look at historical events like sieges. Resource shortage, dangerous environment, social collapse - all that can be expected in post-apocalyptic world. And people did survive. Eating whatever they can find or catch, leaving in cold, and filth, getting sick, witnessing death and other horrors… People survived.

Unless you get killed, or shoot yourself, you would wish you came prepared for that kind of times…