US' GDP per capital is more than 6x than China's GDP per capital. China has a bigger population, and when China's GDP is the same as US, its per capital GDP will still be 1/4 or 1/5 of US. Even it loses the first seat as a country, its people are still better off than others.
"Better off" is no consolation when your country is being rolled over by a more powerful adversary.
The British were richer than the Germans in 1940. That didn't prevent Dunkirk. The Americans and British were richer than the Japanese in 1941. That didn't prevent Pearl Harbor, Manila, Hong Kong, Singapore, etc.
