It is a metaphor that they are still working class. You can earn 500k-1M/year in salary and be working class. Your monthly expenses may be > than your salary and you need it to keep working to get at the same QOL.
I live in an exurb of DC, in one of the highest cost of living areas with one of the highest median income in the world.
I have 3 kids who are all in middle and early high school (the most expensive time) and a mortgage and literally just did the math on what my MINIMUM income would need to be in order to maintain a extremely comfortable lifestyle and it’s between $80-100k a year.
Anyone making more than ~100k a year isn’t living paycheck to paycheck unless they are spending way more than their means - which is actually most people