There are meaningful qualitative and cultural differences between, say, late-career professionals with owned homes and 401ks sufficient to maintain standard of

There are meaningful qualitative and cultural differences between, say, late-career professionals with owned homes and 401ks sufficient to maintain standard of living in retirement vs. people who could maintain that lifestyle or better without even working. That's kind of why we use the term upper middle class - to distinguish true average incomes from educated professionals (law/engineering/accounting/teaching/ middle management and formerly journalism) from landed aristocracy and CEOs of Fortune 100s.