Think of all of the resources and life that have been misused in Afghanistan and the ME while our border is still not secure and our infrastructure crumbles. We're going further into debt, perhaps to the tipping point. Those are primary factors in the fall of great civilization throughout history.
The flaw is that you can’t. They don’t just stay in Afghanistan. They build a terrorist hub. I remember when ISIS was some miscreants in a cave in Iraq. Obama pulled out based on similar arguments that we shouldn’t be there. ISIS didn’t stay in Iraq. They fanned out across the Middle East, and they left absolute terror in their wake - not just in the Middle East but in Europe and the U.S. They didn’t just do terrorist attacks - they led to a massive refugee crisis.