We have been there for 15 years and they are no closer to a nation state than they were the day before we went in. If we left the Afghan government would collapse within a week.
This would be true in another 4 years, 10 years, or 15 years.
We have two choices there. Walk away, or stay forever. But without our forces and the 4 trillion we have already spent there....they will collapse in days. This will always be true.
Not one more American should die for a sunk cost fallacy.