Playing when you know you lag badly

Why do some people play league knowing they're lagging and can't play? If you've already played a game and you know your lag is really really bad... why are you playing more games?

You lag once, just stop playing games for the rest of the night or play a bot game to see if you are still lagging. Don't waste other people's time by trying to play through seconds of lag.

You're just plain out rude if you knowingly play a game with crippling lag. You've knowingly wasted your team's time.