The US spent many billions of dollars feeding Afghanistan, building infrastructure, educating its people, and trying to protect them (especially women) from the Taliban. It didn't work, unfortunately.

Production of opium and its derivatives before it was under US control and after.

These are the only 2 numbers you should look at.

And the US stated the Taliban in order to drag Russia to a war in Afghanistan even before that. There is a 7 years war going on in Yemen, and it I've hardly seen any company discuss that. It's always about something else than the actual war, most of the times it's about money and energy.

[1] https://www.cfr.org/backgrounder/yemen-crisis

Wasn't that a citizen of the US ally Saudi Arabia that "blew up American city"?

Why didn't you destroy Saudi Arabia instead? Because they pay their tribute in oil, and you had to destroy "someone", and Afghanistan was the first in the alphabetical list of countries that met the criteria for destruction?

The fact that said citizen of Saudi Arabia was based in Afghanistan and protected by the country's Taliban rulers may have had something to do with that...

He was exiled in 1991 and ostracized by his family, 10 years before 9/11. He wasn't a citizen of Saudi Arabia when the attack was planned and executed.