The thing about societal breakdown is that it makes a good story. What's viewed as less of a good story is what usually happens. People are social creatures, and they tend to help one another. Look at any major disaster here or around the world and you will see people giving the shirts off their backs to help. Notice how people didn't start shooting each other when Kaikoura got cut off.
Being prepared for adversity is great, but keep in mind that your idea of what a post-disaster world looks like has been heavily influenced by popular media, and that the vast majority of people are good buggers who band together and sort shit out.