I think a huge part of the subtext to this conversation is that nothing is persuasive to the people in question. How many people in this thread have come down off the mountain to explain a point of view that's just bouncing off some dude who's never needed to develop a feedback loop for his thinking?

Calling someone a dumbass in this situation is a kindness, because the assumption is that they're capable of not being one with a little self-reflection.

> Calling someone a dumbass in this situation is a kindness

First they laugh...

Kindness means you're seeking the good of another -- it's noticing the needs of others and prioritizing their well-being.

I can't see how insulting someone pursues their well-being in any way.