That's true, however in pragmatic terms it is no longer possible for any one country to become the "global hegemon".
The USA in 1991 had a level of relative power vs. the entire world that allowed it to become the global hegemon. This is no longer true in the modern world, the USA of today can't even bully North Korea and Iran, let alone any other country. And the USA is openly laughed at in the United Nations, where once they were either liked or disliked (but at least respected) now they are openly treated as a joke.
If China today decided to turn its massive industrial engine solely towards the building of the largest military force the world has ever seen (since the Soviet Union), China might be able to cause terrific havoc and destruction but still would not be able to become the world hegemon, maybe not even the hegemon of the Asia Pacific region.