No, the phrase is about wanting the impossible. "Having your cake and eating it too" is about having a lot of savings, and yet spending all your money. It's about a dog who wants you to throw the ball, but won't let go of the ball to let you throw it. It's about wanting to both have the cake in it's entirety, and wanting to eat the cake. You can't do that. You can't have a huge savings account if you don't save money. You can't throw the ball for the dog if the dog keeps the ball. You can't have a whole cake and eat the cake both.
Of course, I think most everyone understands what the phrase more or less means. But for it to make sense, there has to be some perceived value to having (or continuing to have) the cake. Otherwise, why would anyone want to have the cake as well as eat it?
That value, best I can tell, is in one of two things. It could just be in continuing to have it so that you can still eat it later. If that's the case the saying loses some of its charm - the specialness of using a cake in the adage is lost. With any consumable you can say you can't consume it and still have it. You can't have your gas and burn it too. You can't have your money and spend it too. You can't have your clothes detergent and use it too. Except, you can use some of it and still have some of it left to use later - just as you can eat some of your cake and still have some of it left to eat later.
So what makes more sense to me and what makes the adage a bit more charming is that the value, in continuing to have the cake, that is being contemplated is visual. Cakes are sometimes considered beautiful. They're often decorated. We sometimes make them paying great attention to how they will look. A lot of effort is put into making wedding cakes, e.g., look good. But once you eat part of a cake - once you cut it up to eat part of it - it loses some of that beauty. So, you don't get to have your cake and eat it to. In eating it you necessarily lose it, to some extent, as something pretty to look at. You've got to decide which you want, to enjoy the taste of it or enjoy looking at it. To some extent, you can't have both.
at.