True, but so what? Trying to prevent another 9/11 has cost more lives than 9/11 itself. Leave. Let them stew. Kill as many as we can when they try something. Repeat as needed.
That's the problem. We don't do that.
This thing was treated as a war when it started, and then we started trying to "Win the hearts and minds of the Afghan people".
Since this IS a war, if we are not prepared to destroy them, they will keep coming back to harm us. Basic logic really, but it seems to elude our governments. It's so frustrating.