not 'by definition'. There's a fairly good case to be made that playing by, and being able to set, international norms is in the long term interest of powerful countries. For one because you don't know when you'll cease to be powerful, which will happen given enough time and secondly because even smaller players can cause significant damage when acting without constraint, a lesson several great powers are currently learning for the umpteenth time.
It's very meathead schoolyard bully coded to think that anarchy benefits you just because you happen to be the biggest dude around. It speaks more to the intellect of current leaders than it does to some fundamental contradiction.