It use to be the USA that developed oil fields all around the world now not so much. Just more of the fallout from failed government policies.
How smart is China? They take their trade surplus and buy US Treasuries. Occassionally they buy hard assets like this. But the bottom line is the only thing a US dollar is good for is to buy something from the US.
We wont save our money and make our investments. We spend and borrow to spend and let someone else make the investments. So if we are to have oil, gas, factories, and infrastructure someone has to provide the capital.
At least China likes oil, gas, and omigosh...coal.