[simiones]

I don't necessarily agree even there.

The Viet Cong was a well supplied and well organized army, with significant logistical support from North Vietnam, and would likely had failed miserably if North Vietnam hadn't waited to consolidate its power and accrue supplies (and international support) after the revolution and previous civil war.

In the USSR invasion of Afghanistan, the taliban received ample support from the USA, including training, arms and logistics; again, they would have very likely failed in the absence of this support. In the NATO invasion of Afghanistan, the taliban quickly lost the military war, but ultimately retained their cultural advantage; the regime that the USA tried to install was simply unpopular, and instantly folded the moment it stopped being propped up. Either way, the last few decades of war have not led to some flourishing of Afghanistan as the theory predicts: it remains poor and by all likelihood will remain poor for the forseeable future, as all other war zones do.

Also, in both cases, the advantage of fighting in their own territory was a significant part of what ultimately defeated their opponents.