I've been going through this same conversation with some so-called "libertarians" whose sole solution is to drop and run as fast as we can, let the world go to hell without us. Pull all of the troops back to the US, nothing in Korea, Germany or anywhere else.
Needless to say, I think they are wrong. Afghanistan offers us nothing except opium and bin Laden. It is a backwards, desolate country composed of tribes whose main crop is either opium or hatred of each other and foreigners. When the Taliban were in charge, and supporting bin Laden, I thought we a legitimate reason to be there. Now, I'm not so sure.
I have seen nothing from bho that indicates he or his minions has even as much of a clue what to do as Bush and Cheney did. At least they heated things up in Iraq and drew the BGs there for a long time. When the BGs realized that Iraq was just another word for death to mooslim terrorists, they skedaddled back to Afghanistan and started stirring things up there again.
Not sure what a win looks like, and DC ain't going to give us anything even remotely honorable. I hate seeing our people get killed knowing full well there is no solution. IMO - stabilize the place as much as you can, and hand the keys over to Karzai, telling him "It's yours. Congratulations!" - and leave.