The majority of people I know and work with are mostly in between the inner and outer circle the author describes.
That's a very large group who are paid well (many also sitting on options that will continue to pay well). Being a software/hardware engineer, marketing, finance or other back-office roles does not automatically put you in the "outer circle" on the edge of the middle class.
This is a classic example of an author with a very narrow world view based solely on their personal experience which doesn't look like reality.