@skids48 gunwoo got so many people participating and winning money that if they all took out their money at once the system would collapse since there isn't enough money in the system. Basically a bank run (search up).
I am quite confident that the rule was "who gets the most money after 10 rounds". Technically if you don't cash out - you didn't GET the money. Hence the MC cashing out early - before the exchange died - is in fact the winning move. But a technicality isn't enough to win - however making the opponent lose every single ally he has - including the group he was representing - is enough to win the war - even if formalities are disregarded.