I find it far more insulting, despite being perfectly polite, for people to insist the Earth is flat, than for someone to dismiss them with what is, essentially, an accurate descriptor. I am utterly insulted at the waste of intellectual space and the energy expended in these useless debates when people who lived two thousand years ago had pretty much settled it.
I believe flat earthers are intentionally weaponizing their ignorance as an act of rebellion. So yes in that case it is meant to be insulting, just nit anything to take personal.
