If I bought only guns I "needed" I'd have a 12 ga. pump gun. I could do everything I want to do with a gun, with that except conceal carry I suppose, and I've, to be quite honest, never felt the "need" to do that.
I have other guns, and carry one because I like guns. Sure, I can use it to defend myself, or overthrow the government, or to help push the Martians back into the sea, but I really don't ever expect to have to do any of those.
Another thing I enjoy is the hunt. I like finding guns I don't have, or have never had. I didn't "need" a 10/22 with a Manlincher stock. But I wanted one. Sure, I could have gone to Gunbroker and purchased one, but that's like shooting a fish in a bucket. I had to "hunt" for it. When I found it, it came home with me. Took a few years of watching the same stand, but it did show up.