I comment a lot when I poop or when I'm in the metro or when I'm just chilling for a few minutes, and I just skim the front page for things that look interesting enough to comment on. You'd be surprised how much comments you can get on a day if you comment on a lot of posts.
I just like to comment I guess. Never knew it was this much lol. 2.5k in 8 months almost seems fake to me, can't imagine I have that many comments here.