They have several fucks to give actually.

1. Strategically valuable position for accessing central Asia and the western borders of West Taiwan (eat a dick, CCP) - had we not given up Bagram AFB of course.
2. Some of the world's largest rare earth metal deposits, essential for modern electronics and semiconductors, and one of few accessible deposits outside of West Taiwan.
3. Opium, 70% of the world's supply of natural opium

I don't disagree they want the whole thing de-stabilized, but they can accomplish that by letting the Taliban run things like 7th century Bedouin thieves under Sharia. Easy peasy. They don't need to park NATO assets there and spend over $1 trillion to do that. They spent that money for the 3 above.