We’re not the world’s policeman. We don’t even have the moral authority to claim to be, especially when our own nation has fallen apart legally, Constitutionally, morally, ethically, culturally, socially...
Even if we fixed our problems, it’s not our job to be policeman to the world.
American hegemony is under attack, you're right. But the world is the world is interconnected. By default, we're the world's policeman whether we want it or not. China is next in line to replace us but I don't think the world wants them to call the shots.