While I didn’t read the book, I saw the movie Charlie Wilson’s War with Tom Hanks. I thought it was a pretty cool story, but I definitely agree with what you briefly mentioned at the end.
Our assistance to the mujihadeen equipped elements that would eventually become the Taliban. It is not difficult to connect the Taliban to Osama, and on to 9/11. Would Osama have been empowered if the US hadn’t armed the Afghanis? Who knows?
It could be argued that even without US intervention in Afghanistan, the Soviet Union would have eventually fallen, leaving the mujihadeen in power. Osama may have flourished in that environment equally well.
There is a cruel irony however that when we invaded the country we were being attacked by some of the weapons we gave the Afghanis so long ago.