There is a passive aggressive sort of insult going around. It happens when two people are in a disagreement of some sort. When the details get complicated, one says this to the other:
The implication is that the other’s argument is irrational. And that they’ve lost control emotionally, which led them to logically unfounded conclusions.
It is another way of saying, you’re crazy. Essentially it’s saying, screw you.
People who deploy this device, more often than otherwise, are the ones who may be unhinged. They lack sufficient self-awareness to understand their own motivation. They believe they’re expressing some real empathy.
On rare occasions I have found myself in disputes with someone who, in my view, had indeed “lost it” to some extent. I would never condescend to asking, even in that circumstance, whether they’re mentally or emotionally okay. It’s cheap, dirty pool.