What should I do with a highly upvoted comment that is factually false?

Question

I saw a comment that is based on common misconseption and upvoted in to stratosphere (HNQ effect).

What should I do?

Posting a comment response seems futile (past HNQ effect, no matter how good my reponse is, 40+ upvotes on original comment means it will always be signaled as "correct" one, and mine will likely remain unseen below a long thread).

Flagging seems to rarely work when there's a purely content correctedness dispute on most SEs, as the flags like that are frequently declined as "only flag things that require moderator attention".

Answer 1

This has already been asked on MetaSE. To sum that up a little bit, if the comment warrents flagging, flag it. If it doesn't, don't. If there is something wrong about that comment, feel free to add your own comment pointing out what is wrong. People can upvote your comment as well so it will be more visible in a long thread.

After you have done all you can remember to just move on. You can't be expected to fix everything.