Oh, well... I'm one of the jokers... and a longtime collector with about 60 Leitz lenses, and just one Voigtlander 15mm (to use)...
... for me, it's only a matter of joking a little on the collectors' breed (that is, on, myself too... I'm sure that one could laugh looking at the number of FILTERS I put together in 25 years... and hasn't finished): of course, collectors are of different depth-of-pockets sizings... one looks for top items like "last 100 Noctiluxes" or "Leica I with Anastigmat / mint", another chases for old filters or cases or arcane Visoflex accessories...
BTW, I think Leica has done a rather right job with this kind of collectible: a great improvement on the inflation of "M special models" of years ago...