Wow, that's pretty impressive. The most I've had on any forum is about 4,000, and that was after a solid 5 years of activity. Everywhere I've been, though, I've been considered a valuable member; it's less about post count and more about post quality if you ask me.
I had a member once that would reply to every single post anyone made when he was online, no matter what it was. The problem is he seemed to be online 18 hours per day so in any given day he'd post 300-350 times. We started calling it his forum, lol.
I'm the most active member on my forum, but the second most active member on my forum is pokeraussie. He only has 22 posts, but I know he'll be a long term member, because he's a member of another forum that I'm active in, and he has over 2000 posts on that forum.