*middle class primarily from active income, but also passive income and 
with enough assets to not fall into poverty during hardship*

Then there's going to be a lot of Americans who deem themselves to be middle class who are really high proles with white collar jobs. In effect, you'd have to be a $500K managing director to really be "middle class" by this definition. Meanwhile, an accountant and teacher couple consider themselves to be middle class despite only owning one home and some investments that sit in a retirement account.