If There is One Overarching Reason Why We May Lose in Afghanistan

It will be because of the blatant corruption and influence-peddling of the Karzai regime. And we are willingly climbing into that bed.

I suspect that it is fair to say that the Karzai regime is roundly hated by most Afghans. It may get to the point, sooner or later, that the Afghans will conclude that they would prefer the primitive Islamic brutality of the Taliban over the large-scale narco-corruption of the Karzai brothers. And then it will all be over.