I shop for six people, (this includes four teenagers) so our stockpile is likely very different from someone who stockpiles for just two people.
Let's talk cereal---since we can usually always get it for free or close to it.
A family who goes through five boxes of cereal per week (eating cereal for breakfast and as a late night snack) might buy 100 boxes as that is only 5 month supply for them!
A family of two would not need to buy 100 boxes just for themselves because I doubt a family of two would eat five boxes of cereal in a weeks time!
So, for a larger family, it's really not outrageous to stockpile 100 boxes of cereal when you can get it for free or close to it!