No, it's just a question of priorities. A friend who is definitely not the 1% has a home theatre in his house. Anyone that's upper middle class can afford it, and from there it's a question of "do I want it?"
Come on, duuuuude… I am talking about whether such things* are
commonplace (they’re not), not whether cases of non-rich people with some sort of home theater
exist.
And to reiterate: by “actual home theater” I mean a high-end, dedicated room with cinema-like construction, seating, etc. and equipment that significantly reproduces a cinema experience. Not just a regular room with a big screen and some speakers, in front of a sofa.
And of course, it’s not “just” a matter of priorities: most Americans simply don’t earn anywhere close to enough money to afford such a luxury. The median household income in USA is about $71K. In many parts of the country, you’d pay 10% of that just on the annual rent for the space to house the home theater!
Then remember that half of households make less than that — in many, many cases significantly less — which certainty doesn’t leave any way to spend tens of thousands on a home theater.
*with the photo as a reference, which I’d guess at being a ~$20-40K home theater, including construction costs to raise the floor, install the built-in cabinetry, etc, plus seating, sound panels, and the AV gear.