This is what people mean when they say that Americans have no class consciousness. If you work for a living you are a proletarian, if you invest for a living you are not. There are a good chunk of people who make well over 6 figures as a salary (lawyers, doctors, etc) that experience pressure from the same type of economic forces as average workers - inflation, cost of education, housing, medical care, childcare, elder care - all of these things are only going one way even if some workers are more insulated from these factors than others. That said this is a bad article and not clear, but there again, some low end writer on yahoo not understanding class in a marxist sense shouldn't really be a shocker.

Did they ever try living within their means

A million ain’t what it used to be.
To retire from wage slavery with reasonable comfort in America today is to have saved up enough capital to live off of the 4% rule, and that means say ~$1.5–5M, depending on location.

If you’re one of the increasingly very few with a decent pension, things aren’t so different. While you don’t have direct control of the capital, you’re still living off its spoils.

That's because there's no such thing as a middle class and it's all subjective

Remember, a retiree that owns a home that appreciated in value up to $1 million or more is a millionaire. That's a very middle class thing to have when retiring, at least for now. In a major city that's a Craftsman 3-4-bedroom bungalow. And this is before accounting for the retirement account middle class people need to have in order to avoid having to sell off their home in order to survive.

It's nice to have those things and many people don't have them, but they are exactly what you got with a working wage about a standard deviation above median.

Segment the data by age and you'd have something to talk about.