I suppose Americans do have a naive optimism--I've always perceived British culture in general to be cynical and negative, but that may simply be in comparison to my own optimistic culture. I attribute a lot of that to history. The fall of Europe's empires in the 20th century was the failure of their grand national experiments, and on top of it, much of the world faced immense death and destruction during the wars of the 20th century. Europe, China, and Japan were destroyed in WWII, Korea and Vietnam faced significant destruction in their wars, and most of the communist states faced significant internal destruction through mass murder of various kinds. America largely escaped this level of destruction.
Good point. I think a lot of a culture's attitude is based on cultural memory, which comes from lessons learned (or not) from history.
Americans abroad are often elbowed about how young their country is (ugh, I lived in Beijing and they always trot out 4000 years of Chinese civilization. Nevermind the CCP is only 80 years old), but what this means is relatively less cultural baggage. Americans have less cultural memory to look backwards at and reference (and a lot we see back there like destruction of Native Americans, black slavery, etc is painful to examine), so as a result Americans have no choice but to look forwards.
We also don't have all that old stuff. Over in Europe they still have castles and palaces from medieval times. Buildings that are centuries old. With rare exceptions, Americans knock down old buildings and build new ones.
