It's actually an explicit religious expectation to prep for emergencies. I believe the generally understood requirement is a 3 months supply, but I'm not LDS, so I don't know the details of Mormon practice and variations therein.
What's interesting to me is that Judaism doesn't have any kind of similar requirement. There you also have a history (or at least a stereotype) of having to pick and up and move in response to religious persecution. I wonder if it's because in reality the gaps in time between periods of stability and persecution were often quite large? I don't think Jews have historically seen themselves as a wandering people as much as outsiders have seen them that way.
Mormons, meanwhile, had to move from place to place in quick succession over less than half a decade. It's another reason why LDS Church feels like the ultimate American religion: prepping is baked directly into the religious practice.