I’ll go out on a limb and say quitting to strikes could be the most demoralizing way to lose a fight.
Liver shot TKOs, I’d say, are the nastiest. Your head says, “Fight on!” but your body goes, “Forget about it, I’m done!” We’ve seen high-level combatants fold and falter with their faces grimacing in ungodly, unexplainable pain. At that point, you really have no choice but to quit.
Leg kick finishes come in a close second. But unlike a vicious blow to the liver, this one will make you second-guess yourself for a few moments.