Why do ppl cancel the game as they win, I assume there is some benefit but don't I don't understand. Please enlighten me.
There are no benefits from quitting a game when you are winning, there are only disadvantages. You lose ELO and Karma points. Plus you lose credibility among your fellow players for not finishing games.
The most likely reason why you see people leave the game when they are at the point of winning is because this game is full of bugs which causes people to be kicked from the game. And the only reason for this is that the developers freaking suck at programming! We are YEARS past the release of this game, it's still broken in so many ways, and somehow the developers have the audacity to let people pay money for this...
I'm wondering if it isn't that they quit, but that the bugs (as Olim mentioned) mean the game running on your device gets the signal they left the game before it's realized the game is done, so it displays "all players have quit" and then "you've lost" when it suddenly realizes the game is actually over.
There are all sorts of weird quirks in the interface... I'm not sure they all impact ELO, but sometimes they do (like all players really did quit, it told me I won, then I left the game, it told me the game was still in progress, and then it docked me the ELO I just won when I quit the game a second time [because there was no game]).