Depends how you define "upper class." And "constant dollars."
I don't find this post very persuasive.
First, $75,000 household income is hardly "upper class." You can't even buy a house on that income in many areas.
Second, those "constant dollars" are deflated by CPI or some similar measure, which understate inflation due to flat screens, iPads, and computers getting cheaper while the cost of necessities (housing, food, and energy) increases. I am certain that $75,000 "constant dollars" in 1967 bought a lot more house, food, and gasoline than it buys today.
Finally, this is household income, and largely reflects the shift from one-income families to two-income families. Needing two incomes to scrape by is supposed to be good news?