Because he is meant to be a democrat, he is meant to care about people, and should be tryinf to stop the armageddon that will occur if he causes the resumption of the slide of the global economy to the point where it can only support a small fraction of the current world population.
The republicans say 'everyman for himself', so if they let the US default and cause misery to millions, then they're not betraying their ethos.

Obama has to give way first, I don't even know why he's bothering to play chicken with them......its not just him thats playing it, he's playing chicken with the lives and livelyhoods of others, he should know he cant win this game (unless he genuinely does have bigger b**** than the republicans indifferent stupidity....or unless hes just stupid)