Don't care. The occasional human who might see the comment still makes it worth it. Even if they don't change their behavior, they've been reminded that they are hanging out at the nazi bar.

It's important to remind people of what they're doing, when they're doing something like that.

No, he's downvoted because he's saying objectively false things like "Musk is a mass murderer", and subjective but unproductive things like "he's a Nazi". You can dislike Elon Musk and make that point in a mature way that actually leads to a good discussion. People do that all the time and don't get flak for it. This poster has chosen to be incendiary, and people dislike flamebait so it got downvoted.