As most commenters note, the youth aspect is the real differentiator for the middle class. All this is hard as soon as a family is in the picture, health concerns go up, etc. Frustratingly, most successful entrepreneurs are much older, so a case of "youth is wasted on the young."
Source: Had a 5 figure salary in the bay area for years and it was fine until it wasn't.
Ex: I can argue that VC funding is much worse than having paying customers in your space and the luxury to pivot & explore until things work. Having to double down your growth bet every 18mo or die trying is a real killer. People get confused by thinking the VC path is awesome because VCs only fund good companies, but that doesn't mean it helps them, just that the company was good. Back to my main point, I wouldn't say VC funding is the kiss of death, but it a bad fit for many and arguably most companies ;-)
My point was that part-time pure paid consulting while trying to start an (under-)funded product business is one of the worst things you can do. Would-be founders end up never needing to commit to the riskier venture and having a hard time disentangling form consulting. Source: decades of startup founding and employment experience.
At some point the middle class becomes unlanded gentry.