a) If I'm being brutally honest, it's attention. Human beings enjoy attention even if it's totally dumb luck. I could say for this HN crowd that the traffic translates to revenue or some kind of practical benefit but honestly, it just felt good to get attention for something I created. That triggered a serotonin response in my brain that made me want to come back. I would assume it's similar to a HN post you submit making it to the front page?

b) They're real in that I get tens of thousands of comments and people actually reply. Most of the comments are reactions and jokes but I enjoy the thought that someone took the time to comment just like how I'm enjoying having a discussion here on HN. Whether or not it's meaningful is entirely subjective but probably goes back to my answer in a) - I appreciate the attention.