It is a primitive behaviour because it fosters racism and hatred for others instead of cooperation. The one thing we do not need more of right now is hatred, there's enough of it in the world.
Edit: It is also one thing if a private person holds his opinion (however detestable it might be - I don't care) and if we get this shoved down our throats on a large scale via all types of media and politicians. The latter is what I feel is offending.
There'd be no society, institutions, states, healthcare, education, families and friendships without cooperation.
Furthermore, entire social theories are built on the idea that selfishness is the driving force behind all human behavior. I could quote Nietzsche or Schopenhauer, but there are also contemporary examples (Dawkins and Singer, to name a few). I don't know if I agree with them or not, but there's plenty of conceptual drilling to do before dismissing them as "sociopaths."
An exponential curve, by definition, does not decrease over time.
The US "owes" China a trillion USD because the Chinese, investing on a national scale, need a safe investment that can support trillions and trillions of yuans. And in that regard right now, the US is the only game in town.
China's GDP growth is high, but that's because they're starting from a GDP that's much lower than that of the US. As with any logarithmic curve, growth starts quickly and then becomes harder over time. China has a ways to go.
The number of cars sold and the number of children enrolled in school are indicators that China does indeed have a much larger population than the US. Almost all of the BRIC nations have large populations, but are still in the process of turning that into wild economic growth. We'll see.
Other than the missing context for the numbers you provide, I agree with your general sentiment. There is a bit of schadenfreude among the US media whenever China struggles economicallly. This is probably because China is the US's biggest economic and military rival now that the Soviet Union is gone. It's natural to cheer for your team and boo the other team. I wouldn't take too much offense.