When one of my comments get downvoted, I usually reread it trying to figure out why. Quite often, I realise I didn't explain my point very well and add some better explanation. That usually stops the downvotes and adds some upvotes.

On very rare occasions, I make a point that turned out to be just wrong and not salvageable in any way. If it lead to an interesting discussion, I leave it in place because it still provides context to that discussion, and I admit I'm wrong in another comment.