I realized it today. It is the same impulse that drives my friends to hoard ammo or reloading components.
An example. You learn to reload. All is well. You buy a couple of hundred primers in the various types, some powder, and you make some ammo. You observe that there is a price break to buy a thousand primers. Next time you get a thousand. Moving along, you use a couple of hundred and you feel understocked so you buy another thousand. You have established a floor, the minimum number you feel comfortable having. Next time you buy five thousand. Well above your minimum, but wait, it becomes the new floor.
Then there is a shortage. There was panic buying at some point several years ago and the supply and manufacturing did not keep up. There were outages for a while. If you needed large pistol primers and didn't have a supply, you were out of luck. People remember that. They buy ten thousand. That sets a nice base, they don't use them, they are the emergency reserve. They go back to buying a thousand here and there and working from that, maintaining the reserve that has become their minimum.
Ammo the same way, in whatever quantities are the baseline.
Now it's toilet paper and it's everyone. Might be 48 or 96 rolls, but there's now a minimum stock that people want on hand. Store stocks will not recover until people's attics and garages are filled to the new minimums. There's nothing to be done about this except ramp up production for a while.
Humans and human behavior can only be observed. Telling people to be comfortable when they have an open eight pack of toilet paper is now impossible. The stores are empty, rolls are being snatched off the pallets before they can be unloaded, and having eight rolls is like having the fire warning light on in the cockpit. More must be found.
It will sort out. Our grandchildren will wonder why we felt the need to have 96 rolls of TP in the garage at all times, just like we looked back at our grandparents that lived through the Depression and wondered about the things they did.