Aside from preps for just in case. I stock up for two primary reasons.

First my folks grew up through the depression. A well stocked pantry was always a must. A pantry with at least several months worth of staples plus assorted odds and ends was the norm. Not only for them but also most of those around us. I was taught that was how it was done.

Second is economical. You stock up when things you regularly use when they are on sale. And now making fewer trips to the store adds up. Now you think about saving gas because of its price. I only live about a 15 minute drive from major chain stores. There is also the saving in time. There really isn't much difference in time between a full cart and a couple of things. Call it an hour to an hour and a half for a quick trip. Time to and from the store. The time to get around the store. Then the time in line. With a full cart call it 2 maybe 2 1/2 hours. Consider the savings when you make the trip once or at most twice a month verses 3 or 4 times a week.