This is not my understanding of the class system. It's not divided evenly mathematically. Many years ago, this was most likely the case, but I would argue that unless you're at least in the top third percentage for income, you probably aren't living a "middle class" life. Features of what we used to call middle class, and I argue still should, are things like owning a home, going on vacations, and having a retirement account.

Reducing the idea of middle class to statistics normalizes things like living paycheck to paycheck because that's what median income earners in this country do. That will never be middle class to me. That's working class at best and more like working poor. I would love for everyone to have what I think of as a middle class life, but it's sadly out of reach for most of us.

Middle class is not median income. It is a lifestyle that is enabled by income that fewer and fewer people can attain.