I define my uses, and try to aquire a gun fill each "niche" (Usually but not always in that order
). For my situation, I have about a dozen guns that I can articulate (read: rationalize) a clear reason for owning. I also have a mil-surp collection that I own/shoot/restore purely for fun -- mentally, I separate these from my "modern" guns.
For me, my needs include HD, Urban SD, Wilderness SD, Skeet/Trap, IPSC, SHTF/Paranoia and introducing new shooters (this last goal is vital if we want to keep being allowed to accomplish the others!!). I also desire the ability to hunt anything in North America, though I don't actually do this (yet).
I'd like to add a good SHTF rifle, probably M1A, but for the moment the "go-to" guns are either the levers or the 30-06. I guess my sense of paranoia is even more anemic than my wallet. I'd also like to add a couple of .22's, so that I've got a .22 with a similar technique of shooting to each "big" gun.
Unless I take up a specialized sport, any new guns I buy will either replace something existing, or I'll have to admit to myself that there is no practical justification for them
.
Rationalization aside, if you've got a good centerfire rifle, a 22, a shotgun, and a handgun in 38/9mm on up, there's nothing in North America that buying another gun will do for you that moderate competence with your existing arms wouldn't allow. Beyond that, they stop being tools and start being toys. Is it possible to have too many toys? I don't think so, but I TRY not to convince myself that they are anything else.
My "niches" (and current occupants):
Rifles
Bear defense (Guide Gun in 45-70)
Big-game rifle (Rem 700, 30-06)
Varmint rifle (Tikka T3, .223)
Trunk rifle (Beat-up old winchester 1894)
Practice/Newbie rifle (10-22)
Handguns
Primary carry gun (3.5" 1911)
Backup/ankle carry gun (snubbie 38)
IPSC gun (5" 1911)
Woods sidearm (Blackhawk in 45 Colt -- pretending to be a 44 mag)
Practice/Newbie automatic (Ruger 22/45)
Practice/Newbie revolver (Smith airweight snubbie .22)
Shotguns
Trap/Hunting/Practice (Winchester 1300 Black Shadow)
HD/Skeet (Winchester 1300 Defender)