I have a job1, involving technology, but not anything having to do with the Internet or web technology. If it did, I probably wouldn't have a website.
There's something to be said for keeping up your professional knowledge in your field2, but there's something else to be said about doing something outside of business hours that you enjoy doing. Put another way, it's nice to be able to spend time doing the kinds of things that you want to do instead of what someone else tells you you should be doing.
That's what this site is. It's something that I work on when I'm not working on work given to me by someone else. It's work that I do because I want to it. Will it help me in my job? Probably not in the traditional way3, but it does help keep me (relatively) sane, which, to me, is a lot more valuable.