Had OP phrased the post differently, it may have met the forum guidelines.
Instead of "Is the millionaire next door dying," OP could have asked, "Is the millionaire next door still a viable path to wealth? How so?" And the wall of text after the title would need to be one of inquisitiveness, rather than some post-mortem that ends like a LinkedIn post with "agree or disagree."
The second option opens the discussion up to actionable advice, while the first just has people debating whether or not small business owners can still build wealth.
And no, the millionaire next door isn't dying. Just like people focused on flashy job titles (doctor, lawyer, etc.) 25 years ago, they focus on flashy job titles (SWE) today. All the while, a blue-collar business owner can accumulate wealth without needing to appear wealthy with fancy cars and expensive clothes just the same.