I think it is a difference in mindset. There is no harm in preparing an emergency stash of supplies, no different than setting aside an emergency fund for cash. I like to shoot for an "heir and a spare" with many shelf-stable items, including food, toiletries, and cleaning products. That way, I have some extra on hand, but most items can be used up within a year or less, so they don't go to waste. It also means that if a store is out of a favourite product, I don't have to settle for something I wouldn't normally purchase. I'm not going to wave a finger at anybody who is putting together extra supplies for emergencies, in fact, I would encourage it.
Hoarders, on the other hand, seem to grab everything they can with little thought to how they will use it up in a reasonable amount of time. They also don't seem to consider whether something is even an item they would want to use. I wonder how many people grabbed "all" of the toilet paper, with little regard for if it was quality or not. For me, unless I am desperate, I do not want to spend my money on something I would hate using. There seems to be something almost primal about it...perhaps an "I have the lion's share and you get nothing" sort of outlook. It is like what people can grab equates to a prize of sorts. I don't really understand it and can't speak to the minds of people who need to grab the most. This is real life, not and episode of Supermarket Sweep.
I basically have a grocery store in my basement. I always have. I rotate my supplies, but we do have enough to probably last four to six months (not a balanced diet, but not starving). I grew up in an area where, in the winter, you might not get to the store more than a few times, with weeks or months between trips. I watched my mom prepare us for winter and have carried that "prepare for the unknown" throughout my adult life. It didn't matter if we were living in California around earthquakes and wildfires, or nor'easters in New England. I have always kept extra supplies on hand.
I currently have two Kirkland packages of toilet paper in my basement. In fact, I just bought the second one today, as we finished off one of our other packages. I always keep at least one or two full packages on hand. I don't consider it hoarding because I have a limit in mind for our family's use and it is reasonable for us to go through it in a reasonable (much less than a year) amount of time. I follow a similar type formula in my head for how many boxes of pasta we keep, how much flour we go through, and how many tubes of toothpaste are on hand. This is our everyday purchasing model. When Covid happened, we didn't rush out to buy 12 Kirkland packages of toilet paper "just in case." We know what we need, purchase accordingly to maintain our supply, and if things go south and somebody buys up all of the toilet paper or spaghetti noodles, we try not to stress about it and restock when supplies in stores resume. In fact, having my stash of items likely helped others during the Covid-19 buying frenzies, because our family didn't need to run to the store to stock up while supplies were low and others needed them more. Our basement storage supplied us, as well as our adult daughter with much of what we needed, greatly limiting trips to the store for two households.