I own two guns and that's likely more than I'll ever need. I maintain them, practice with them so my aim doesn't deteriorate, but that's about it. They're tools to me in the same way hammers or screwdrivers are. I suspect that puts me in the minority here, but I don't watch for what new guns are coming out or lust after different ones, the ones I have are fine.
Knives, on the other hand, are my hobby and I could probably buy one every day and still find more that I wanted to at least handle. No idea why they hit me that way so much more than guns but, well, I'm here on Bladeforums, not on Glock Talk, so I can't deny that they do.