You could just state that I'm wrong, or you could explain why you think that. The second is valuable, the first is a waste of a comment.
Edit: why would anyone downvote this? Other than the owner of the useless comment anyway... For the record, comments on HN should have substance, it's in the guidelines when you signed up.
It's my policy to downvote any comment that complains about downvoting. However, it would be better in this case to not even respond to GP's inane scribbling. Trust the downvoters to get around to it eventually.
I prefer giving reasons why behavior should be corrected as opposed to downvoting and hoping they can divine why they were downvoted (like whoever downvoted my comment with the reason why his comment was bad, I have no clue what they objected to, so they accomplished little.)