Most of you don't get it because you probably think exclusively about the money and not about the pride in one's game, reputation and honor. Literally anyone can get a set/game ahead and run away. There's not much to it. That's pathetic. It's also cowardice and an admission you're not confident you can reproduce this. If you're this desperate for a few bucks, maybe pool gambling isn't for you. There's more to gambling in pool than just cash. You should only quit when behind or even.
There's no glory in quitting as a winner. The idea is to not only win, but to have the loser concede this by them quitting. To beat them down where they want no more. Get them to say mercy, or cry uncle or tap out. So long as they keep wanting a piece of you, if you're ahead - you should play. This is the only way to prove you're the true winner since it is unanimous. Your opponent confirms it, not you alone. When you quit ahead, you're just declaring yourself winner. This is the equivalent of when you were a child and some kid in the middle of a game or arbitrarily just declares themselves winner like some brat. When opponents quit when behind, they agree with you and confirm you the winner. It's that simple. Surprised so many people don't understand this basic concept.
The fundamental difference is in defining what the "game" is ...the quit while ahead types think the game is literally the set or whatever they won and ran away with. The quit only when even or behind crowd believes the "game" is the struggle and contest between two people facing off, regardless of the games/sets. The "game" doesn't end with the completion of a rack or a set, it ends when the loser has had enough.