I think that if we get to the point where there are real shortages then there will have to be rationing. Until then, though, I don't think it is stupid or selfish for people to buy more than they need if they have the space to keep it all and can afford it.
I was brought up to believe that good housekeeping involved being prepared for emergencies, so have always had things like pasta, lentils, tins and packets of non-perishables in a box, along with bottled water to cook it. I also have candles, a primus stove and things like that to hand - again, in case of (unspecified) emergency.
We often shop at Costco, so buy loo rolls in giant packs anyway, and things like toothpaste comes in boxes of 12. I wouldn't make a special trip because of Coronavirus, but the chances are that we will have overstocks of random items just because we always do
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In the event of fire, flood or pestilence we could manage for quite a while without leaving the house at the best of times. We might end up eating unusual combinations of ingredients, but we wouldn't starve.
I bought in extra in case of a hard Brexit, (and as Elegran says, we haven't left yet, so we still don't know how that will play out), so there is more 'stuff' in another box in the spare room.
If necessary, I will get more as and when it becomes clear what might be in short supply. It is what I have always done, and I don't see how it is wrong to do so - as I say, if there are actual shortages, I will be happy to comply with rationing, and in fact I can stop shopping altogether for a while.
If or when I find that I don't think I need packets of soup, and it is clear that vegetables are plentiful, I will go back to making my own, and donate the packs to the food bank.