You can always win
[Start Rant] Okay, lets start this off with a little background. I'm the jungle Quinn this game, at all stages of the game I was doing fairly well. Our Blitzcrank didn't do super well, but he wasn't the worst thing to happen to us. He had a sightstone and more support items early on, sold them to be a bit more useful to the team after our Lux AFK'd. Our Caitlyn refused to help the team early on, instead insisting that her and blitzcrank sit under the tower at bot lane so she could farm. Even during a team fight at mid lane, she stayed bot lane and kept farming. Our lux was doing well, picking up easy double kills while I roamed to provide pressure to all of the lanes. She got caught out a few times, and I assume got tired of hearing "stop getting cauight" from caitlyn and left the game. During this match, one we were clearing winning, our lux decided to AFK. From that point on we lost objectives simply because of the pushing power of 5 people versus the defending power of 4.
Background done, here's the point of the thread: Our Ryze, after Lux left, immediately gave up. I had spent most of the early game making sure that he won his lane against yasuo, making sure that he had the tools necessary to be the late game monster that I know ryze to be. But that didn't happen. Lux left the game, and he wanted to surrender. We voted no, and he immediately started running into the enemy team 1vs 3, 1vs4. When we asked him to stop, because at this point I was easily split pushing and taking their towers [along with assassinating whichever one of them I could catch out] he told us there was no point because we couldn't win because Lux left.
We had a gold lead, a dragon lead, and no one on the enemy team could even try to fight me, but Ryze gave up.
Just because you have an AFK, just because the game isn't going flawlessly, it doesn't mean you can't win. It doesn't mean that you should walk away from your computer, it means you should play smarter. If one of your team is a great split pushing champ, set up wards to make sure y'all can alert that person when the other team comes for them. If one of your teammates is highly fed, and you know they can carry, than do whatever you can to make sure that person is kept safe from the enemy team. If that means everyone on your team has a Mikaels to ensure to cc ever hits that person, than do that. Don't just give up because you don't like the situation that you're in. [End Rant] You can always Win.