I dont think man-cave and collection room are mutually exclusive.
What if you put a tv in your collection room? Or a stereo? Does it then become a mancave? The collection is still on display, but you can watch tv too. What does it take for one to become the other?
Most guys with man caves dont actually buy dollies or expensive toys.
A lot of man caves are dedicated to sports or nascar or football or to drink.
Or for playing video games. A collection room CAN be a man cave, but a lot of man caves have nothing to do with collecting figures.
Man cave is code for " stuff that my wife hates but i love"