We don't exchange the products of our labor for money because we want it, what we want is the porducts of the labour of other people.
And why would you want to labor of the other people if thing can be done faster and better by automation processes.
Do you need that many prostitutes ?
Any amount of automation will ALWAYS require someone's labor behind it. Even if you have machines that can use 3D printers to print out more machines and can fix/maintain those other machines, you still need someone to take the time to invent, design, and improve those machines. 3D Cad design and engineering is A LOT of work, and requires a lot of different specialized education. You would need people who have specialty in electronics, physics and engineering, software development, chemistry (to create new stronger materials), architectural design, and for robots that grow food, biology and botany. After all those people get together, you'd also need specialists in 3D engineering design and CAD software design, as well as resource and operations management to make sure all materials for these machines can be acquired and are used correctly. Getting specialized in these fields takes A LOT of time and work. Why wouldn't these people ask "Why am I busting my butt, spending YEARS to learn this stuff, just to provide these goods/services to people so that those people won't have to work or learn, and have everything they want provided to them?" Sure, there will be a few (maybe a lot) of people who are interested in these fields, but why would they want to do this work for others without asking for anything in return? And what if there is a shortage of people to do these things? Will someone have to force people to work on this?
I think THE ONLY way RBE is even possible is if machines replace the only type of work they still can't, which is creative thinking. But, once machines are able to think and invent as well as humans, our race becomes obsolete, anyway (especially since machines will likely figure there's no point in spending their resources on us)