They have nothing to lose by holding out.
On a side note, why is it never suggested that the Dems give in?
Because you don't give in when you are being held hostage, or the next time republicans will ask for more because they are SO sure that democrats will be safe bullied victim and not allow the US to be damaged economically.. Imagine a Republican president being held hostage by Hardcore leftist until they raise taxes above 60% for the wealthy or they ask for specific funds to address minority poverty. Republicans wouldn't agree to that either and we would keep doing this dance forever. This shyt has to stop.