It's a well-known "paradox" known as Jevons Paradox. Given enough efficient use of a resource, overall usage could actually far outpace the efficiency gains. E.g. use of coal got efficient enough that travel via trains using it became possible, which led to way more usage of coal.

How far does it scale? Because I imagine there must be diminishing returns at some point. And even so, having a lot more renewable energy also means less cancer.