Yes but when you have a small apartment living space you can't have months worth of food stored.

Taking short term opportunity of sales of singular items makes sense. I often buy meat depending on what's for sale, but not months worth.

Maybe once in a while you can buy bulk for dry-store items like pasta or rice.

That's the point though - richer people with larger houses and sufficient refrigeration space at least have the option to save money by buying in bulk. Then again, richer people need a way of signaling their wealth to others so will typically by more "premium" products, so the two effects largely cancel each other out (as it is, the stats certainly don't show that the rich spend absolutely less on food than the poor - but certainly a significantly lower % of their income).

Having to buy a larger house, a larger refrigerate, a larger transport vehicle to get the option to potentially buy in bulk. When in effect what they actually do, and data shows this, they buy to much perishables and then throw them away.

So I can buy that yes, there some potential places where this theory could potentially apply.

However, if you derive a social theory from these effects, I would like to see some evidence of this effect being really large.

Compare that with the land use situation I keep bringing up, we have prove and had it for a long time that density and walkability does massively reduce the living cost of poor. This was modled in detail for California for example:

This video shows the results of some modeling done for California by a famous urban planner: https://www.youtube.com/watch?v=fUtdFbK4YG4