I don't think you are using a conventional definition of upper class, or that it is interchangeable with capital class. I also don't think these are the definitions for the Post you were responding to.

That said, I agree eight figures is about the right number for when a family would not have to work assuming that the capital assets are managed appropriately.

I think high value labor is the main path between lower class and middle class. High value labor plus smart investment of surplus capital gets families from middle class to high class. The path from high class to Capital class, as you call it is, primarily return on Capital management.

To get from Capital class to Kennedy class requires a significant windfall or luck, as you would expect for tail end of a Pareto distribution.