Did you mean this as in, 100k is not quite middle class, or 100k is over your bar for middle class? Here in Seattle, I make around that with 1 yr exp and certainly don't feel secure or comfortable with it.
So, sure, the parent could make a different choice, and move to a lower cost of living area, but then they'd be making significantly less, and might still not feel particularly financially secure.
Even now, with many companies realizing that remote work is ok, and planning to allow some form of it permanently, many also plan to change (lower) people's salaries based on where they end up deciding to live, even if they do the exact same work.