Is there enough people doing that to justify the scale of robot based manufacturing?
I've only seen costs for stuff go up with inflation, and most people don't have wages that track inflation. The owners benefit from the cheaper costs, but nobody else does
define "stuff"
When adjusting for inflation, most things are getting cheaper. It is only a few goods that are getting much more expensive after you adjust for inflation and almost all of those things have one thing in common: government meddling and regulation.
to other people employing, manufacturing or investing in the robots
Gains in a society goes to those that are doing something useful to contribute to increase productivity, such as providing the labor that increases the productivity or providing the capital to make that increased productivity a reality. While they won't get the gains, bystanders to this process benefit from cheaper costs due to increased productivity.