Americans individually are probably the most optimistic people in the world. The optimism might be myopically fixed on getting a promotion or winning the lottery or breaking the plate spinning world record. But if you don’t have some big project or self improvement scheme then many people (and most traditionally successful people) will give you a wide berth. People without big dreams might as well have already kicked the bucket.
Regardless of the government this culture is infectious. I think of Nikes famous tagline “Just do it” probably describes America better than any anthem or crusty document.