I gotta go with the Iraq invasion.
What we have paid so far in the war woulda gone a long ways towards rebuilding the towers and the economic effect of their loss.
Probably a wash in terms of US lives and limbs, but no contest if we count dusky hued furriners (even at a discounted rate) and casualties from the war keep growing daily.
After 9/11 we had the sympathy of nearly all the world. Compared to our might international coalition in Iraq…
9/11 resonated in the American perception of our country and its place in the world. So has our leaders lying the country into invading a sovereign nation.
If it were close, I’d still have to go with the self-inflicted harm. This clusterfuck in Iraq was entirely avoidable, and nobody did it to us other than ourselves.