Sure but the amount of carbon you burn to get to that rock, excavate it, process it, move it, etc, etc is non-trivial. A computer and projector on 8 hours of day is a drop in a bucket to that.
In fact the cost things like PECVD or dry etching is so disproportionate compared to drilling a hole in the ground, that I'm willing to bet a computer is the equivalent of hundreds of years worth of a blackboard with chalk.
Really, I recommend anyone look into this stuff. Just to get silicon to the purity and precise structure to just start chip fabrication: https://en.wikipedia.org/wiki/Czochralski_process Imagine the whole supply chain, from smelting metal for wires and cases to plastic molding to storage, economies of scale truly are vast.
>that I'm willing to bet a computer is the equivalent of hundreds of years worth of a blackboard with chalk.
As someone who grew up near a limestone mine, I think you greatly underestimate how much work it takes to get rocks from the earth. I've seen some of the largest machines in the world working there. Its an huge operation.