You haven't shown that it's physically impossible though. Scaling doesn't work that way, not even in the physical world does it work that way. As the side length of a cube increases the surface area increases with the square of the side length, and volume increases with the cube of the side length. When considering the effects of scaling a system it makes no sense to just multiply all numbers by some constant. The question of how much energy Bitcoin would consume if you scaled it up cannot be solved, even in approximation, by blindly multipling it's current energy usage by a constant.