We don't all buy stuff for the same reasons. Some of us are professionals, who can write it off on their taxes. Some of us are hobbyists; new Poser stuff is like entertainment, like other people might buy a book or video game or movie ticket. Some of us are "prosumers" - very serious hobbyists, who may do some paid work, or hope to.

I suspect another big factor is that we're part of our consumer societies. We have a lot of money to spend (compared to most of the world), and we sometimes spend it on things we don't need. Because it's on sale, because it looks really cool, because we might need it some day. I confess, I have things in my runtime which I have never used, and this is probably true of a lot of us.