I pursue needs most of the time, like the need for one of everything... That may be a joke but I'm not convinced.
I like to buy guns for jobs though. I hunt less than I used to, but that is just a time thing. I like to have a few deer rifles in different configurations due the the terrain and weather diversity of where I hunt.
I also get caught up on certain cartridges or cartridge families, and I want to be able to reload and, if possible, cast bullets for whatever I'm shooting.
Lately, my first son (almost 9) has gotten really interested in shooting, so I also get to buy guns with him in mind as well as the other three.
I also have started getting a little past need for JUST a tool, and have picked up a few rifles for their aesthetic value. I love blued and fine wood, always have, but function usually comes first for me except for a few nicer rifles.
I also like to build guns, and sometimes a project just screams too loud and I have to take it home. Most of the time these get sold or traded once fixed up, but not always... I do keep all the guns in one safe, but it is getting REALLY tight in there....