When I was just a kid, we were told "nuclear energy will make electricity so cheap, we will take the meter off your house." didn't happen.

In my experience, economies of scale always have hidden costs. Your digital technologies will not be the exception.

That 3-D printer will have to consume raw plastic to produce anything, and that plastic will end up in the waste stream. I appreciate your enthusiasm, but I'm not convinced you're seeing the whole picture.