This seems backwards from what we actually want to do, but also has significant compliance concerns.

It's obvious how to tax consumption. It's (fairly) obvious how to tax income. How would you tax savings?

Is buying stock in a company "saving" or "consuming"? Is buying Bitcoins "saving" or "consuming"? What about gold coins/bars? What about guns and ammo? What about a collector car? Artwork? What about a house for personal residential use? What about a house for rental/income use? What about just holding suitcases of $100 bills?

It seems like there would immediately spring up a system of "not treated as savings" savings mechanisms. I seriously doubt that you'd accomplish your intended accounting simplicity...