Getting downvoted doesn't feel good, but it happens to everyone. What works is to look over your comment as objectively as you can and try to find what might have evoked a downvote. If you find something, correct it for next time. If you don't, remember there's such a thing as a misclick.
Usually—not always, but at least 2/3 of the time—it's fairly obvious to a neutral observer why a comment was downvoted. Try to be a neutral observer in your own case.
Does karma do anything past something like 500? I think a lot of people see voting as curation more than punishment. Humor get buried pretty readily because it's fluffy and "reddity" not because OP is a monster.
Or factually incorrect statements. Even made in good faith they usually get buried if the answer is in a sibling but not when the answer is in a child post. It's not always personal.
For this reason I sometimes wish that people could stop complaining (with varying level of irritation) about being down-voted without been given reason, a fairly common occurrence. OTOH, helpful people will sometimes (probably not the down-voter) provide a reasonable explanation, which is OK too.
This could be a decent solution, though, if their explanation would need to be public. Basically leave a comment in order to downvote (with an indication that this comment was made in connection with a downvote), and therefore then also the ability for others to vote on this person's reason to downvote you.
> ## Downvote Explanations
> Often on other sites, a user would have his or her comment downvoted without explanation and then edit their comment to ask why they were downvoted. On this site, voters must choose a reason before downvoting comments and those votes are tallied and shown to the original commenter.
> For submitted stories, downvoting is done through flagging (also requiring a valid reason) and these flag summaries are shown to all users.
I like the limited cardinality of Lobsters downvote options because it reminds me of acceptable reasons of downvoting, because “I disagree but don’t want to write a comment” isn’t a choice.
If "everyone else is wrong" is not your thing, cherish your downvotes too: we're all wrong sometimes.
There should be consequences for down voting to suppress abuse of the privilege.
If explanations of down votes are not acceptable, then a cost of say 100 reputation votes per down vote would discourage misuse of the privilege.