I haven't read all the comments throughout this thread. So, if this point (if it is one) has already been alluded to, my apologies!
Although probably applicable, I've always had a bit of difficulty accepting the term or concept of "hobby" for what audiophiles are preoccupied with. It seems, to me, that the common denominator in this or what is at the core of what all audiophiles do is the visceral love of music. That's what kicks it all off! The term or concept of "hobby, I think, probably applies more to those who are constantly or frequently "upgrading", swapping out components and/or tweaking their sound systems in search of that elusive holy grail of the "best" sound fidelity. For those, however, who achieve levels of satisfaction with their sound systems that they can live with for considerably longer periods of time and, thereby, "upgrade" much less frequently, even when they can afford it, I think are more lovers of music than hobbyists.
Does that make sense?