According to the article, winning at poker requires incredible psychological toughness. Yes, there's the luck of the draw, but "the odds are with the players who win the mental game." Said one of the top players: "You're always trying to figure out what your opponent is doing."
Players are also "extraordinarily observant" and "tough minded."
I've not watched poker on TV before (though it seems to be on all the time), but now I'm curious to see these guys in action.