So roughly 100 were killed for every american dead in 9/11. Thas's a harsh punishment, US certainly doesn't know what mercy is . Edit: missed by two orders of magnitude. Still, a lot. Also: not a blame, just observations.
In hindsight, the second war in Iraq was a disaster of course, but why blame the US for every bad part of the outcome? What about the Iraqis? What about Iran? If the US hadn't started that war, the regime may well have collapsed during the Arab spring.
As for Afghanistan, that conflict started well before US involvement after 9/11.