It was for things that I eat every single day as a part of my diet, but that I knew were likely going to run out (like nuts, raisins, salt-your-own crisps, peanut butter, etc).
I've been avoiding panic buying of random shit precisely for the reasons you've spelled out. I didn't go near any of the stuff most people are hoarding (not that there's any left even if I wanted some pasta or rice).
I'm still hoping/expecting to go out every few days for skimmed milk, eggs, cottage cheese and bread.
Although I am still young and healthy, the issue I have is that I live alone and have no family still alive. If I were to become ill, I'd have to rely on myself for food and drink. if I were unable to physically get out of bed, I'd pretty much be fecked. And if I were too unwell to go out shopping, I'd be equally in trouble.
So I may not be vulnerable from an age point-of-view, but I am vulnerable from a support network point-of-view. Having a few packets of nuts, raisins or crisps by my bedside is about protecting myself rather than trying to get one over everybody else.
For what it's worth, I've also timed it so that I've been eating loads of takeaways the last couple of weeks. Now I'm going to start dieting for the next couple of weeks (eating minimal amounts of food). Then I'll go back to normal. Hopefully that'll be enough to get me through.