Lots of people derive pleasure from having something others don't, be at an art collection, an antique car or even a partner.

This suddenly strikes me as a very important issue of study.

I would be extremely relieved to find a large body of experimental evidence that would confirm the hypothesis that all those people enjoy this for other reasons, such as status display or signalling, rather than actually having part of their brain directly place actual value on being the sole owner and user of something without notions of availability or other logistical problems of sharing stuff, i.e. as a terminal value in some sense.