I think he has said before they are seeing a marriage counselor.
As for what the therapist said, I agree. Money can indeed make you happier if you are living paycheck to paycheck.
But once you have enough that you don’t have to worry about food or shelter for the rest of your life (and most of us on here are or will be in that state), then the rest is gravy. Adding more gravy will have a much smaller effect on your happiness. I’d say the same thing about real gravy on my mashed potatoes by the way.