It's like any other fascination that can overtake you.
Could be guitars, sports cars, girlfriends, horses or Lladro collections.
If you have to have them all right now even if you can't afford them, you're on the road to trouble.
But unlike girlfriends or Lladros, guns mostly keep their value and unlike horses and girlfriends, don't mind if you don't pay attention to them for awhile.
In some frames of reference, extra guns are hard economic goods which could be bartered if necessary.