I wonder what percent of the population owns their mansions outright --- to me the wealthy are those who don't have to work for a living but can live comfortably off their investments or inheritances. The middle class requires a paycheck --- most would have mortgages and may have little net worth --- but accumulates some wealth through the years by paying off their mortgages so an income wouldn't be needed after they retire. Hmmmmm, interesting. I'm not rich, but I own my own modest $150K home on one acre here in Central Texas. Paid cash for it when I moved here. Now, when I retire soon, I'll still need a pretty good income to keep that house. The property taxes, insurance, and minimum utilities (water, elec, sewer, trash collection, etc) cost me about $520 a month. And that's without a mortgage.
I consider myself lucky and pretty well prepared for retirement, but I'm still gonna need an income to maintain even a paid for home.
I think that's the problem --- or definition of middle class --- you have to have some kind of income or save up some kind of retirement so you'll have income. In this country only the independently wealthy and the poor never have to worry about money or how the bills will be paid.