A coffee cup I once saw had the answer to this, I believe: "Life is like bungee jumping, you never know what'll happen until you reach the end of your rope." You can say what someone (you or anyone) can and can't do all day, but you'll never know for sure until they have to. It's amazing how people respond differently when in that do-or-die instant.

Besides, as has been said, the crew was not simply able to play - they were destined to play. Their entire lives, and that of their guardians, are written by the fact that the did and will play the game, and succeed to at least that level. Ouroboros has lapped himself, ladies and gentlemen, and he's still going.

Ordinary rules, ordinary expectations need not apply here.