I know plenty of people in the lower middle class, middle class, upper middle class, and the rich. You’re deeply out of touch with what it’s like to be in the middle class and the rich if you think it’s lower stress to be in the middle class. The rich self-impose their stress and could give it up if they wanted to. (And I watch those who do and they take it very easy) The middle class don’t impose their stress, it’s an externality they cannot control.