What about regions of the world where almost nobody make $75K? Is everybody sad there? For example: India. Anyone there could be poor but could belong to a loving family with reasonable health but earn "only" $20K. Maybe all they can afford to do in the evenings is go for a walk, tell stories, or sing songs. But what's so bad about that?
Many kinds of goods are cheaper now that they were historically. What % of Americans have indoor plumbing? What fraction of people had indoor plumbing 500 years ago? Don't people with indoor plumbing have a reason to be happier? Back then you couldn't buy good dental services for any price. Even poor Americans now in many ways live more comfortable lives than royalty did a thousand years ago.
I suspect that 99% of humanity have no real identity of their own. They are not capable of focusing on their own lives, doing what they can do to improve, and enjoying what they have. Instead, people judge themselves by comparing to those around them, "Keeping up with the Jonses". There's no surer way to make yourself unhappy.