Why do they want the USA to lose in Iraq?

No, I'm not talking about Al Qaeda, disaffected Sunnis, or other Islamist terrorist groups who seek for legitimacy, glory or publicity by fighting the USA in Iraq.
It's the left-wingers in the USA who seem to find a perverse joy in each American death, revelling in the suffering of families and enjoying a vindication of their anti-war = anti-Bush position. But Christopher Hitchens points out the absurdity of this position:

How can so many people watch this as if they were spectators, handicapping and rating the successes and failures from some imagined position of neutrality? Do they suppose that a defeat in Iraq would be a defeat only for the Bush administration? The United States is awash in human rights groups, feminist organizations, ecological foundations, and committees for the rights of minorities. How come there is not a huge voluntary effort to help and to publicize the efforts to find the hundreds of thousands of "missing" Iraqis, to support Iraqi women's battle against fundamentalists, to assist in the recuperation of the marsh Arab wetlands, and to underwrite the struggle of the Kurds, the largest stateless people in the Middle East? Is Abu Ghraib really the only subject that interests our humanitarians?

Hitchens is right on the money. He also points out the bankruptcy of deciding your war stance on pre-conceived ideology (easy to do from a comfy USA home) instead of what you actually want to happen in Iraq, given the current things that have *actually happened* and that you *cannot* go back and change (i.e. there is a war in Iraq, and it will go one way or the other):

There is a sort of unspoken feeling, underlying the entire debate on the war, that if you favored it or favor it, you stress the good news, and if you opposed or oppose it you stress the bad. I do not find myself on either side of this false dichotomy. I think that those who supported regime change should confront the idea of defeat, and what it would mean for Iraq and America and the world, every day. It is a combat defined very much by the nature of the enemy, which one might think was so obviously and palpably evil that the very thought of its victory would make any decent person shudder. It is, moreover, a critical front in a much wider struggle against a vicious and totalitarian ideology.

I have briefly wondered, myself, why anti-war demonstrations and sentiments are focused solely on Americans, and not on the people who are aggressively pursuing death and destruction in Iraq. Of course, the answer is likely one of the following:
a) the war is the USA's fault caused by their aggression, so they (never *we*) are to blame;
b) protesting where people ignore you is futile;
c) Iraq is too far away and too expensive to get to, to mount massive marches;
d) if this were tried in Iraq, you will be in mortal danger from those who want war (usually considered Americans, and, strangely, not those who are killing Americans.)
Imagine, if you will, if all human rights groups and world media attention suddenly began to roundly condemn and protest insurgency, and world organizations and funding was diverted to Iraqi causes. What would happen to support for the insurgency then?
But, of course, in many people's minds, that is the equivalent of support for Bush.