Interesting how the author is so focused on money and material things. When I grew up in the 50s the term middle-class was more about complete family. War widows and their kids were only gratuitous middle class. Divorced and single parent households were lower class.
Money was part of the definition. But it was not the single focus of the author.
Yes! Middle-class is much more than money. Typical of a modern-day author!
Without a middle-class in terms of values and monetary security, there is NO society.