Anybody who's in the US middle class can have a low stress life. Most don't because they want things. (Mostly they want to compete with people they view as their peers.)
If it were really about stress you’d see a difference in kids who have a parent working in the public sector.
There's lots more but I mean - surely that's sufficient to get the idea across?
Not sure what country your experiences are based on, but I consider American middle class to usually be salaried people who are homeowners (maybe with mortgage, fair enough), so several of the points you raised don't apply. That said, of course, it's a pretty fuzzy category.
Please try to behave nicely on HN. There is no need to insult others here (for instance, by saying that they don't get something that is "obvious").
In other words, "rich" (from the global perspective).
Idle brains rot.
It's spot on tho that comfort & saftey provides the opportunity for genius to develop.
Why do you have to insert social commentary? It's off topic.