Online games are fun are always fun at first, but they can boring very very fast. I tend to just 'rush' my opponents. haha.
In short, ask your freinds. It's their response, and give a reason for doing so. Instead of just saying 'this is dumb, let's play something else'.
Wait, but when you said 'there is no hope for team's victory'; does that mean you're losing? If you know you won't win, I suggest kamikazee with another freind to attack another civ.
But yes, you CAN replace yourself or anyone else for a computer.