I disagree.
If we were to stay after 8/31 we would have needed to ramp up our troops.
The Taliban was already in control of half the country.
We've been there for 20 years, its cost us $2 TRILLION & many died or were maimed & will never be the same.
There will always be a threat somewhere.
The evacuation should have been handled better.
As for nation building, that has to come from within, and it might somewhere down the line. Vietnam comes to mind.
For as many flaws as the US has, many Afghans would love the choice of living here.
Do something positive.