I'm just middle aged and lost all energy for unproductive discussions. The second another poster posts something genuinely hostile, like "touch grass" kinda shit, I'm just done talking. Also if we're six comments in and the other guy won't even admit to being wrong to the thing he said on comment one, despite me doing twenty minutes of research to prove conclusively that he's wrong, I don't want to waste another second of my life on him.
I gotta have 10% of the "disengage" comments on this site.
I don't think there is ever a wrong time to disengage from a situation. You don't owe anybody the time and mental energy it takes to continue the discussion at that point. Especially on the internet, where there shouldn't be an expectation that the other party is ever coming back to the discussion, just close the tab and move on.