[There is no deterrent from an outnumbered group hunkered down in defensive positions waiting to be slaughtered. Ask the Brits how well that worked out when they were there previously. ]
https://www.khaama.com/taliban-battered-in-kandahar-60-killed-786876876/
The Brits were financed by loot and/or taxes from conquered lands. Afghanistan is a wasteland. There was no benefit to had from it. So they crushed the Afghans and left.
https://en.wikipedia.org/wiki/Second_Anglo-Afghan_War
Afghanistan has been repeatedly conquered in the past, typically as a way station to some other destination. Most left because it wasn’t really strategic other than as a way station, and the costs were high, due to its remoteness.
The Taliban spit in our faces by helping to attack our financial and political capitals. It still exists. The Taliban will need to die of old age or despair before we leave. Or such attacks will recur.
Actually, that’s pretty ideal, given that we have command of the air. The Taliban is losing dozens of men a day. That can’t continue indefinitely.
Neither can we.
Fuel for those aircraft costs well over $400 per gallon to deliver to our forward air bases. All types of supplies have similar exorbitant costs. And much of that money goes into the pockets of our enemies in Pakistan and Afghanistan.
Wars of attrition are won by superior logistics. We don't have them. We will run out of money long before the Taliban runs out of fighters. We have been there long enough to see a whole new generation of fighters raised to adulthood. They can breed them almost as fast as we can kill them.
Besides, defensive wars of attrition are an extremely stupid idea that almost always fails with useless sacrifice of good men.
It's time for us to leave.