I know this sounds hard to believe for some. But today, agriculture takes up about 2% of labor, and manufacturing about 10%. And we consume about 2x what we did per person compared to the late 1970's. So, cut back manufacturing to about 4% of the labor force and use another 3% of the labor force for distribution. Voila, 10% of the labor force is used to sustain a 1970's level standard of living. Everyone else can improve their themselves, create arts, study nature or contemplate the nature of existence (that's sarcasm there).
In your universe the universal law is that the robot builders have (collectively) nigh absolute leverage over the rest of society. Without the angel assumption they would slowly (or quickly) use that leverage to amass power.
People wouldn't live in rags or whatever but all secondary economies point to providing value to the robot builders.
But wages are always relative to prices. If everything is being made by robots that nobody has a monopoly on then everything should be very inexpensive. Having to work for the same nominal wages as you had in 2003 is not that much of a problem if nominal prices are now 5% of what they were then.
The problem comes when you have some kind of corruption or distortion or regulatory compliance costs keeping some prices high (see: housing, education, medicine) even as general wages are flat or decline, or just grow less than those costs.
If less labor is required for tasks A, B and C, then that frees up people to do new tasks D, E and F.
It is untrue that there is a fixed amount of work to be done, so when some of it is automated, then that necessarily creates unemployment. That's the "lump of labor fallacy".
https://en.wikipedia.org/wiki/Lump_of_labour_fallacy
It's also fallacious thinking to assume that every person must be employed working for wages.
If someday the economy as a whole can produce everything people need by employing 10% of the people to build robots, then we can organize it such that the people who like to build robots can do that, and the people who like to paint, or sculpt, or hike or sail can do that.
There is no universal law of the universe that requires the 10% of robot builders to own everything on earth, and the other 90% should live in rags, filth and sickness.