His point was that Gates already has all the money a person could ever want, so he no longer values it enough to waste any time trying to make more. For a normal person, money is often valued more than time, which is why the majority of us spend most of our days working for someone else. If I ever became wealthy, my time would become more valuable than money too, and I would spend most of my time doing the things that I really want to do. Right now, However, I need money more than I need time.