If the stacking approach works at all, it must be because it is self-supporting. The material, once lifted, holds itself up. At first it seems a bit silly that

If the stacking approach works at all, it must be because it is self-supporting. The material, once lifted, holds itself up. At first it seems a bit silly that the bottom layers aren't lifted off the ground much at all, but if a tower is N meters high, the average height of each block is N/2, so that's only a factor of 2 loss. (For example, if each block were 1m tall, a stack of 100 of them would be 100m tall, and the average block would be 49.5m off the ground.) And of course also because concrete is a combination of cheap, strong, and heavy. All of these serve as multipliers for energy storage practicality.