As a civilization, we have barely scratched the surface: You may have only heard of the Kardashev scale since Elon Musk brought it up, but it is rapidly gaining traction as a concept. It was originally proposed by Russian astronomer Nikolai Kardashevin 1964, when I was just one year old. The Kardashev scale distinguishes type I, II, and III, also known as planetary, stellar or galactic civilizations.
We as humans are not even fully planetary yet, because our solar production level only uses part of the total solar input on the Earth surface. With the Terafab announcement, Elon said that in order to scale properly, going to space solar is needed, as expansion on the globe itself runs into constraints like land area, and lots of other things like people complaining about solar or windmills near their homes.
And going to space is actually doable: as further scaling on Earth becomes ever more difficult and costly, the freedom of less factors influencing deployment in space actually makes the arithmetic doable...
