How can a puppet destroy a country. He is just a diversion, a scapegoat for those who profit from the dismantling.
Obama has a dual character. He is both puppet representing a faction controlling a polity, and master capable of diverting the polity's course in irrevocable ways. He is both subject and object. He could not have come to power outside of a specific context laid out legally, politically, normatively, and psychologically. But having achieved power as the physical expression of American Leftism Obama is capable of diverting the course of an empire by actions which cannot be undone. His interpretations of law have set precedents that will be used by all of his successors. This is most evident in his expansion of presidential powers. Obama has diminished Congress in the same way the Emperor Augustus diminished the Roman Senate.
Obama is a tool of the capitalist system which he adjures; however, within the context of the capitalist system Obama chooses winners and losers. In this manner he diverts the course of the polity. Obama has achieved what he believes to be great things, but at a terrible price in terms of incompetence, social cohesion and national solidarity. He could have been so much more had he not have been so deeply flawed. He is as much a narcissist as was the Emperor Caligula. The United States will survive Obama, but it will never be the same.
I'm not sure that he really failed her. I think he tried his level best and some of what he tried didn't work out. I think he could have done better with Katrina.
America could only remain the sole superpower as long as it was perceived as essentially benign by most other nation states, movements, and groups. He could have prolonged the unipolar moment and preserved it as the Five Good Emperors preserved the greatness of the Roman Empire. But he wasn't cautious. George misjudged the fear he would create in the international system as well as the steadfastness of the American people to engage in hostilities for more than three years. His lack of caution and misjudgment had the unwitting effect of throwing away an empire, and opening the way to Obama. In turn Obama has proceeded to unintentionally create a new international order.