I think there's a common pattern in personalities that like fantasy and sci-fi material that makes us all find owning a tangible peice of our favorite fantasy universe appealing. I'm finding it hard to categorize people like you asked, but I think there's more folks out there (in this sort of genre) that collect some part of it than do not.
I know that prior to the POTF2 launch, I collected a wider variety of things, like random toy lines, laserdiscs, things like that. I was always looking for one particular aspect to focus on, and didn't find a match until there was a resurgence in SW merchandise to chase. Now I basically collect anything I find compelling in the SW universe, and only want everything from the 3-3/4" toy line.
But, I have a group of friends that are in a lot of ways just as much into movies/Star Wars/fantasy/whatever, but have very different collecting habits. One friend now collects movie props exclusively, and with a good explanation. He explains that for the dollar amount he used to spend on action figures every week, instead he could take that total and actually own a piece of the movie. So he has all sorts of random props now.
Another friend dumped his modern Kenner/Hasbro stuff and went to "high end" and now focuses on Master Replicas, Code 3, and props, with a limited vintage toy selection.
If we were all truly "everything" collectors, Sansweet would be out of a job.
Finally, I don't know anyone that admits to being a fan and is content with just watching the movie. It comes back to the personality type and basic like of the genres. Someone into Star Wars, or LOTR, Aliens, D&D, Transformers, anything like that, seem to have a little something tangible from that series to own.
Just my take.