Contrast this with a person with many millions or billions in wealth. That person literally does not ever need another paycheck to live. In other words, they do not need to work to live, unlike a typical worker making wages.
What does that mean?
The 300K is the paycheck (annualized). It's what they use to pay expenses to live. If the paycheck goes away you no longer can pay those expenses.
i.e. of course they need the paycheck to live.
Are you suggesting someone who made 300K once can now retire instantly and never again need a paycheck? It doesn't feel like the above quote is fully thought through.
Now, sure, if they've been making 300K for a couple decades, hopefully they've stashed away enough to eventually retire. But that's a very different statement.