The person who can buy in bulk pays less for already having more room and money.

Buying cheaply requires capital and space. You need the money to purchase more than you need now, and somewhere to keep it, and the people without either pay more per unit for everything, permanently. It is one of the more reliable ways in which having less costs more.

Where you can, notice this before concluding someone manages money badly. If you have the capacity, using it is sensible rather than shameful. And if you help anyone with their finances, storage and cash flow are often the actual constraints rather than discipline.