The amount of stuff I have has never led me to rent a larger apartment than I otherwise would've, so it seems like the marginal cost of more stuff is zero for m

The amount of stuff I have has never led me to rent a larger apartment than I otherwise would've, so it seems like the marginal cost of more stuff is zero for me, at least for now? It's not like I'm renting additional storage space or anything (which is an option in the basement of my apartment building, but that certainly wouldn't be worth it). All the extra tools, parts, and such that I have fit into two normal sized moving boxes, which can easily be stuffed under the bed or take up a shelf in a closet. I have more of a problem with books than I do with tools and parts.