It is usually shills/bots. They aren't interested in debate as they are incredibly vicious and mean.

They are ugly and offensive so that anyone reading or lurking psychologically doesn't want to be on the team being attacked. its an old and effective psychological tactic.

Example: if I said that I believe in Bigfoot, I would not get vicious ugly personal attacks on an actual conspiracy community.

Ideally there would be discussion, proofs on both sides, and then other unique theories about Bigfoot.

But with flat earth, it is someone asking a question or providing evidence, and getting downsized within seconds, with tons of accounts activated to launch personal attacks.

This will persuade on-lookers, some of whom will become anti-flat earthers themselves. And go on to mimic the attacks they saw. When all along it could have been bots or paid shills that started it.