Well, I agree that the Taliban wouldn't have liked it and would have been a nuisance for a while. But they are not capable of being more than that. And as things were beforehand, the Afghan army would have still been in operation and bearing the brunt, as it had done for years. The foreign presence gave it whatever spine it had.
So the situation would have returned to what we had until a few months ago pretty soon.
The Biden administration is making other options sound as bad as possible to justify its own decision. They've exaggerated the cost by using 20 year figures [$2tn!!!] because annual ones are small. They accumulate 20 years of casualties [more than 2,000 dead!!!!] because annual ones are very low. For myself, I didn't see Afghanistan as anything to panic about. I liked the fact that we - the western allies - were continuing to battle Islamic terrorism. The policy worked so well Americans forgot it existed and thought domestic terrorism was a much worse problem. It helped our relations with Russia and China for the western allies to show they would cooperate with one another and seem resilient.
And by the way, it wasn't only America that was there. You had allies there too. The UK was prepared to pay a share of the price. Canada was. France was. We lost some people, invested in Afghanistan like you did. And I would have been content to continue with that as a better option than stepping aside to let the Taliban back in. To put up with one sort of inconvenience to avoid a different, worse one.
It wasn't primarily about nation-building. It was about protecting ourselves from whatever festers over there. That's the cost of the decision to leave. And the execution of it emboldens the countries that wish us ill.
You can certainly say, I judge it is better to leave. But there's a price to it. The responsibility for the costs accrue to the folks who thought abandoning Afghanistan was a great idea. But everyone bears them. So if China attacks Taiwan or Russia takes over Ukraine or some nutty Moslem blows up buildings in NY, that's the corollary. Personally, I think those outcomes are much worse than staying and we have risked them by leaving.
We've shown again that as time passes, western democracies give up. Not a great precedent.