More than Vietnam? More than WWI or WWII?

I disagree with this verdict pretty strongly. You can make a case that the cost-benefit of Iraq and/or Afghanistan was clearly in the red. You can make a case that the opportunity cost of Iraq was large because without it, the US could have accomplished A, B, or C.

But you also have to grapple with the fact that regime change in Iraq also had outcomes—such as the Arab spring, such as the evolution from an autocracy which was counter to American interests to a semi-functioning democracy that is loosely aligned with American interests—that are net goods.