When one end of the conversation overshoots the halfway point, controlling the definitions, admitted facts, scope, and conclusions, it's no longer a discussion. It's not even the Monty Python "Argument Clinic" sketch. It's not even tyranny.
It's a colossal bore.
As both an honest man, and a student history and current events, I do flatter myself that I'm tolerant, can take a joke, and don't get upset quickly. I'm not even angry now.
But, given a 24-hour day as a hard limit for Presidents and peasants, one's good nature accepts a finite amount of abuse.