They're just imaginary internet points.
Also, neither I nor anyone else cares about the points, I don't expect to spend them at the karma store. What I do care about, as I'm sure you do as well, is whether something I said is incorrect and why.
Congratulations. You managed to earn a (deserved)down-vote in a post that crusades against them. :)
But more to the point. HN is an awesome community of very well informed and accomplished people who provide their viewpoints and broaden (my) understanding of many issues. Discussions generate feedback sometimes reflected in the up/down votes we accumulate. So while they may be imaginary, votes serve a very real and useful purpose.