It's not a matter of scale. If people don't have to spend as much on X then they end up with extra money and will spend it on Y. Jobs then shift from X to Y.
This has been happening for centuries. The large majority of people used to work in agriculture. Now we can produce food with a low single digit percentage of the population. Textiles, transportation, etc. are all much less labor intensive than they were in the days of cobblers and ox carts, yet the 20th century was not marked with a 90% unemployment rate.
It's either one of two things. Either post-scarcity is possible because machines that can collect and assemble resources into whatever anybody wants at no cost are possible, and then nobody needs to work because everything is free. Or it isn't, there are still things machines can't do, and then people have jobs doing that.
This has been happening for centuries. The large majority of people used to work in agriculture. Now we can produce food with a low single digit percentage of the population. Textiles, transportation, etc. are all much less labor intensive than they were in the days of cobblers and ox carts, yet the 20th century was not marked with a 90% unemployment rate.
It's either one of two things. Either post-scarcity is possible because machines that can collect and assemble resources into whatever anybody wants at no cost are possible, and then nobody needs to work because everything is free. Or it isn't, there are still things machines can't do, and then people have jobs doing that.