It doesn't sustain, it's not supposed to. Techno feudalism is an indulgent fantasy and it's only becoming reality because a capitalist society aligns along the desires of capital owners. We are not doing it because it's a good idea or sustainable. This is their power fantasy we are living out, and its not sustainable, it'll never be achieved, but we're going to spend unlimited money trying.

Also I will note that this is happening along with a simultaneous push to bring back actual slavery and child labor. So a lot of the answers to "how will this work, the numbers don't add up" will be tried and true exploitation.