Griefer. It's a tool of the powerless to make themselves feel important. The more people respond to them the more important they feel.

Some of them go bat shit crazy when they're insulted. It ruins their whole day and they become more unhinged. Some thrive on that but when proven wrong on something they're smarmily sure about they get unhinged and will try to accuse others of building straw men in roundabout (and in this case sarcastic) ways because they're afraid they'll lose. As long as they can keep people interacting they feel like winners.

Edit: As always, the best way to deal with a troll is to downvote and block. Remember, they don't have to be smarter than you. They just need to get a rise out of you and then they'll keep doing it.

Lemmy is a relatively small place. If you let them, people like this will overrun the whole thing then piss and moan because the community just isn't the same. Do not engage.