My father and his brother build as kids in the 50's. It was something they were both fond of as car guys and he started models for me at 8 or 9 years old to help fill those winter afternoons in LI, New York. We went to car shows and my fathers love of the American automobile was quickly passed on to me, as I idolized my dad. He was a big garage sale/flea market guy so I had new batches of old kits dropped on my table all the time. He kept me well occupied. As a borderline ADD kid, that was important.
I built throughout my childhood and in my late teens I started wondering if this was just kid stuff, because mom still called them my "toy cars". Then I discovered SAE in the hobby shop and was enthralled by the work there. Here were grown men, doing what I loved and making them works of art. I was inspired and vindicated and my dad and I read every issue cover to cover.
I built throughout my addulthood, but rarely as I didn't have a lot of time with the military/wife/kids/etc. About eight years ago, I got back into it. I build now for two reasons. First, I love cars. Period. Second, I have an artistic side that needs to be expressed. I'm not happy unless I'm creating something. Models, painting, poetry, short stories, table top role playing or whatever.
While it isn't "solely" why I build, I'm very guilty of this. I do love to share my work, and I do enjoy the attention it gets on forums or at contests (two a year). I'm aware of this and consider it a character flaw, but an acceptable one. I share on multiple forums and am in two model car clubs. However, this is what I'm into. Models. I do it by myself at home. Not a real social hobby. Contests and forums add that social aspect to it and that is something I crave. I can't help it and don't wish to try. I'm sure it's been noticed by folks here and feel free to ignore my threads if it's something that bothers you. I won't be offended.