Well, judging by what I've seen at CES (Alexis Park), at regional audio shows, at local DIY gatherings, at my former retail shop, middle aged white guys are a serious majority of those interested in the hobby. There are some exceptions, of course, but by and large that's the way the hobby looks. I take that back - CES enjoys a huge influx of Asian audio afficianados.I'll get another chance for a reality check at RMAF in two weeks.
One fairly wild exception - Rick Rubin spent quite a while in the Audio Note room this past CES. While he is, indeed, a middle aged white guy, he has produced the Beastie Boys, Johnny Cash, Red Hot Chili Peppers, Neil Diamond and System of a Down, as well as some rap & hip hop artists (?) There's a weird and wonderful mix for ya!