So what a $millionaire is not in the super rich or even the rich class - well of middle class yes.

1 million dollars in a 401k is not the same as a 1 million dollars in a house. When the median american makes 65k per year and has 45k in disposable income it takes a lot of luck to put a million dollars into a 401K. There are 300 million+ americans, of which only 650k have a million or more in the 401k. How can we call the top 650K middle class?

You can not just count 401k which has stingy limits, I bet that are more than 650k with >1$m if you count other assets as well as the 401k

(excluding your home)

We can assume that the 650k people with $1 million in just their IRAs also have significant other assets. I’m not really sure what you are arguing here.