"$100k" means nothing without knowing the cost of living in the particular place a person lives. As an extreme example, $100k is not "affluent" if you live in a US city like San Francisco or New York. If you want to keep your housing expenses to a reasonable percentage of your income in those places, you're going to be living with several roommates in a small apartment in an old building in an undesirable neighborhood.

Even outside the most expensive cities, we have lots of affluent suburbs throughout the US, and I guarantee you those households have to earn quite a bit more than $100k/yr in order to live there.

Good luck if you're a family of four making $100k in one of these places. Well, you aren't in one of those places; you live somewhere much cheaper.