It's hard to know when it's time to quit sometimes. Most of us can likely remember a few instances when it would have been wise to let discretion get the better of valor.
Still, you trudge on anyway because it's all you know, and it sometimes takes hindsight to realize the right extraction point in a given situation.
Mixed martial artists, though they exceed the average person in most measurable skills related to fighting in a cage, suffer the same issue on occasion.
They don't know when to quit. They're thinking about that next opponent when they should be thinking about retirement.
Here are five bouts that should have been a fighter's last, because he couldn't go out any better than he would have that night; however, he kept fighting because he couldn't see that fact until it was too late.