I fall into the hobby breeder category. While I make a decent little chunk of change from my small collection, I am in no way shape or form motivated to increase in size. I'm right at that point where if I expanded, things would become less relaxing and more like work in my eyes. This also means that when I want to add to a project, or even start with a new species, something else has to move out. I've had reptiles since I was a child and will until the day I die. That said, interests within the hobby shift - plain and simple. If you keep reptiles for 10, 20, 30 years you will probably go through a rather diverse hodgepodge of species. I have always been motivated to work with a wide variety and, since I want to keep it relaxing and laid back with my personal collection, this means sometimes selling off an entire species to someone more interested in them at the time.