I mean.. are you really not aware that the US and China have an adversarial relationship? Both countries embedding spies, industrial espionage, trade wars, soft power projection, etc etc. Power is a zero-sum game.
What kind of power do you mean? The military, economic, and industrial power of China and United States have both been increasing, it doesn't look like "zero-sum".
US and China choose to act this way, but they could stop harassing each other without affecting their own power bases.
US and China choose to act this way, but they could stop harassing each other without affecting their own power bases.