Ever drive a model T? Can you find a 64 Mustang convertible? 1800s vintage tea cups?
Lots of old things are scarce. Arcade games are in the same boat, but you've got MAME and I've got a bit-slice coprocessor and rasterizer ASIC controlled by a 6809 in I,Robot.
Not sure how games are different from other antiques other than the possibility of emulation.