I admit to collecting a bit myself. The only stuff that stays in the collection and not in use is something that doesn't work and is waiting to be sent for repairs.
Or something got as a gift and is totally obsolete.
I have never really bought a rare camera-why buy something you then have to worry about and protect? My idea of collecting is interesting things that I like. Like my Polaroid 100. They made a huge number of them. Yet it looks kinda cool, has that funk flashbulb flash, and still works mostly. My 900 can't really be used, but it is interesting, and for the price ( $30 along with a cool amprosound 16mm projector, two films, and a sears tower camera) it is worth in interest alone the couple bucks it cost.
Besides, collecting allows one to try out all sorts of old or unusual gear. Be it something you bought or something someone offers you because they know you like cameras.
I only have a few cameras I use-the others just sit in their cases waiting for me to find a place that can repair them all. I must admit to having a couple things that I am keeping, and intending to buy that currently only look good on a shelf. Sometimes the fun of obsolete gear is just as an example of failed technology or where tech has been. A giant VHS camcorder isn't collectable, but is an interesting contrast to a newer digital. Only a few years difference and yet compare the size of the things and the resolution they can achieve.