Spending money on aggressive wars almost never benefits a country economically compared to putting the same money back into its economy.
This kind of ignores the fact that war is huge business.

In fifty years when China takes over first place in the world it will be because they kept investing in their country, not investing in an oversized military they used to wave their dicks around the world.
And this assumes China's growth is sustainable. Spoiler - it's not. I mean, I'm no expert, but there's only so many ghost cities a country can build before the bust.