The point is that people shouldn't pretend like what's going on now has nothing to do with the 2003 invasion.
If you hit someone with your car, some would say you have not only a legal responsibility but a moral responsibility to do whatever you can to make things right, even their injuries are so severe that they can't ever walk again. That means paying medical bills and not just running away from the situation you caused.
Iraq may well be the guy who can never walk again, better off as Sunni-stan, Shia-stan, and Kurdistan, but so what? Your attitude is like "well we can't get him to ever walk again so we're just going to stop paying medical bills even though the patient still has bills piling up due to physical therapy lessons in how to use a wheelchair."
What has happened now is linked to the Iraq war, but not entirely. Much goes back long before 9/11, but yes the war had consequences. The problem is that we aren't at the wheelchair stage. We're closer to the end of life stage and how much should be invested in invasive surgery and extraordinary measures for the terminal patient soon to die. What should have not happened was the war, but it did and we excel at winning them. We crushed Iraq in short order because they were never a threat. What we suck at is what to do after and that's because we don't bother to think about the realities of the situation before taking action. That's what the "insurgencies" were all about, the collapse of social order allowed animosities to create further chaos and bloodshed. The next stage is ISIS. This isn't injury and therapy. This is more akin to terminal incurable cancer accelerated by quackery remediation by the west for a hundred years.
In essence we can't fix Iraq or any other nation in the region. We've been expending energy to keep the social pyramid on its tip to keep from falling over and is becoming more difficult as the pyramid becomes larger and more misshapen due to our interference. It's resulted in Islamic rule, 9/11, ISIS, and every time we try to repay with force, even well intentioned, it becomes worse.
Iraq cannot be fixed. The ME cannot be fixed. The pyramid will have to tip and break and the survivors need to rebuild. We owe them to help, but we'll go about it by forcing them to build it upside down again. Humanitarian aid is the only thing which would have merit, and that by NGO's.