The karma matters precisely because it can't be bought (not in any ordinary way, at least). It represents peer acclaim (or conformity to groupthink). If it was bought and sold, the basis for its value would evaporate.
You can easily get karma, if you know how to game HN and the users.
If you post anything in a thread with a clear bias towards something, you can just post something in the same vein, and, depending on the popularity, people will upvote the hell out of you.
Another is to just post something in a very popular thread, and you're bound to receive a lot of upvotes. Even people who would normally have been downvoted through the floor would wind up with a lot of karma. (EDIT: The same applies to popular comments: that's why you see so many people responding to it, because they'll earn some extra karma by piggy-backing on the specific comment.)
I think people take karma way too seriously. There isn't any perfect solution except to change your mind set about what the karma is and does. Compared to reddit, HN is much more rewarding, because there aren't idiots who keep downvoting you for no reason other than latent misery and hatred towards mankind, or whatever may possess them. Downvoting sends very bad signals and stifles the incentive to participate in the community a lot, so the comment would need to be very inappropriate to warrant a negative karma score.
The only suggestion I'd like to make is to make per-thread karma inversely proportional to the popularity of the number of thread upvotes, so the comment karma (quality) isn't a function of the number of views in the thread. (Perhaps the same with child comments versus parent comments.)
If pg can do this retroactively, I think we'll already see some interesting changes for the better - albeit no end-all solution.
Or maybe it just represents "points" -- little cookies -- for the user. You can never have too many cookies.
I don't know. That's why I suggested the experiment.
I think the idea that it represents peer acclaim is not very useful, at least to me. I've heard other high karma folks say (and I agree) that probably more than anything it just represents spending too much time online.
It's also valuable because it eventually grants the ability to downvote.
(It's annoying to see obvious trolls and spam sitting at 1 and not be able to do anything about it. I'm still a few hundred points away, unless the threshold has gone up again.)
