The problem is that the US has too many people who were actually better off in the past.
This is where the pessimism comes from. While a very small number of high-tech areas have gone fast-forward into the future and are way better off, the vast majority of the country has been left behind.
The "problem" here is the globalization of the economy. I like to think of it as an icecube in a pitcher. If you pour water in, it starts to melt the icecube, so the tip will go down a bit, before it's carried up by the water level. The US/EU is the tip of that iceberg. As economies around the world copy the Western world, they're rapidly expanding and improving the quality of life for millions around the globe, while the ones that were in the lead after WWII have seemingly stagnated.
Really we're just waiting for everyone else to catch up.
> Yet, they still have very significant endemic impoverished population clumps
China has problems, but nothing compared to the China of 20 years ago. China is the poster-child of globalization improving the living conditions of the poor.
This is where the pessimism comes from. While a very small number of high-tech areas have gone fast-forward into the future and are way better off, the vast majority of the country has been left behind.
Fix that, and people will be optimistic again.