If you were making $50,000/year you might be able to save $10,000-$20,000 a year by cutting spending. However you'd be able to save infinity more by increasing earnings. If you were making $50,000 and got a raise and were now making $100,000/year a year that would let you save $50,000/year. You aren't going to save $50,000/year by cutting expenses.
There's no theoretical limit to your earnings, however, you can only save at most 100% of your salary.
It's also a LOT (and I mean a lot) easier to cut spending when you earn more.
I think what the GP meant to say was if you increase spending when you increase earnings you'll never save any money.