If you can make feed N people for X, the only reason you can't feed one person for X/N is if you're buying too much of things and throwing them away because they go bad. This can be mitigated by freezing things, accepting eating leftovers repeatedly, making smaller quantities, etc., although indeed it's more difficult.

Yeah but if you have stuff that isn’t freezable, even if you’re ok with eating leftovers, you end up having to buy smaller quantities of stuff else you risk stuff going bad before you eat it. Smaller quantities tend to be more expensive.

For example, I don’t buy milk anymore since I do not remember the last time I have finished a carton. I keep some powdered stuff around because I sometimes use it for cooking, but I don’t buy liquid milk anymore. If I did need liquid milk, I would probably end up buying the smallest quantity of milk available to minimize waste, but they would probably be a much higher per-ounce cost.

That’s what I mean about it scaling logarithmically. If you can buy a higher quantity the prices get much cheaper.

You can always buy evaporated milk

Or freeze it.

https://www.usdairy.com/news-articles/can-you-freeze-milk

I do that occasionally as well. In addition to the dry stuff, that more or less covers any milk need I might have.

My point was that there’s some items that would either lead to waste, or they gotta buy such a small quantity of it that the rate is bad.