Eh, I don't think we need full automation. There are plenty of superfluous jobs today and the number of people to "keep the lights" on is probably 5% of the population or less.
Currently ~60% of the adult population is employed. How do you knock that down to 5%, while taxing that 5% enough to support the other 95%, without taxing so much that working isn't worth the effort?
It sounds like you're advocating for a planned economy with 5% participation, which seems odd given that planned economies haven't worked in the past with 10X the workforce.