Or so is a school of thought of contemporary political economy (read Why Nations Fail by Daron Acemoglu. et. al. )
Example: the cotton gin did not make for a healthier middle class, since the political apparatus barred access to capital (and human rights and civic participation) for so much of the population.
Today access to capital is as easy as it ever was (except maybe '06). The people who take risks are rewarded and there are countless stories of people moving out of middle class.
Below: a chart of "share of gross national income from wages", read this as "Labor Share of Income."
Small business owners and others who get much of their income via ownership rather than wages/salaries are often indirectly but strongly dependent on the salaries of the working class to stay competitive.
So really most people are in the same boat when it comes to these things. It just manifests differently.
The middle class owning more assets than working class sure is better off. But both derive most of their income through wages rather than assets.
Once a certain segment of the population realized that real estate was "undervalued" relative to the potential for collecting rent on the undervalued property - yeah. rent goes up, wages don't at the same rate, more credit card debt. High debt means you're paying nearly all interest, so that ain't going down.
Oh and does anyone actually remember earning a decent amount of interest at a bank? man, those were the days. 12 month 7% CDs, lol.
Since everybody now has a washing machine, fridge and vacuum, the profits fell and the manufacturing just barely sustains itself.
Since the founders / owners / shareholders extracted all excess profits, the companies became brittle in crises, causing them to buy each other until there is just about 1 per continent, possibly 1 in the whole world.
The only way to jack up prices until then, barred burying the whole planet under a pile of planned obsolescence electronics garbage, is to invent new ways to introduce scarcity. Like gating certain features behind a subscription fee.
And temporarily also to lay off as many people as possible, replacing them with automation.
Please elucidate how do you envision next win-win capitalism-based boom. Time savings to everyone have been driving the last one. The only area with a low-hanging time-saving fruit remaining is time on job. Which is exactly the time capitalism seeks to maximize for workers.