What would happen if every state acted like Donald Trump's America?

What is wrong with resurrecting the prerogative of major powers to claim a sphere of influence in which they dictate and others must follow? That idea informs the "Donroe Doctrine" behind the US invasion of Venezuela to seize Nicolás Maduro. Donald Trump seems to believe that, as the world's strongest military power, the United States should be allowed to invade other countries at will. Trump's homeland security adviser, Stephen Miller, says "the real world" is "governed by strength", by "power", so we should get used to it...