So, if you're really interested, seek out and read the French philosopher Jean Baudrillard's "The System of Objects - II A Marginal System: Collecting."
If the title doesn't put you off immediately, his essay has a lot of thought-provoking things to say about the psychology of collectors, the psychological nature of objects, etc.
I'm not going to post his ideas here, because I don't care to support or defend them on an internet message board, especially one for collectors, who may take offense at Braudrillard's conclusions.
I will say he's definitely talking about collectors, and not speculators or investors.