Have you ever downvoted your own post or comment?

If someone else posts a better comment that renders mine superfluous, I’ll often delete mine. But if someone else has already replied to mine, I’ll leave it for the sake of context but downvote it so the better one gets more visibility.

Downvoted? Yes. Intentionally? No.

Yes, if I realized later it detracted from the discussion.

I just here for the first time, I find it liberating, almost daring behavior

no

Why would I? I'd rather just reply to that comment/edit it and say something like "my bad, I brainfarted and misunderstood everything!".