If you're an AI company and you believe your own hype (like Musk seems to), you'll probably believe that you can automate everything from digging minerals out of the ground all of the way up to making the semiconductors in the robots that dig the minerals.
As you may infer from my use of the word "hype", I do not think we are close to such generality at a high enough quality level to actually do this.
Presumes that the surviving humans will not actively disrupt/destroy these automated industries. Which seems highly likely as they will want to scavenge them for anything of value or repurpose them for their own means.
There's lots of implicit assumptions or this would be a book, but remember that Musk has a rocket and wants to colonise Mars, and that Mars is so bad that it is currently 100% populated by robots.
For the billionaires without rockets, there's also a whole bunch of deserts conveniently filled with lots of silicon.
(Or as Mac(Format|World|User) put it sometime in the 90s when they were considering who might bail out Apple and suggested one of the middle east oil barrons, a "silly con").
His lifetime, I agree unlikely, but also I think that will be short: he's pissed off too many other powerful people and will get the western equivalent of Russian oligarchs "falling out of a window".
The economics he talks about are all nonsense. No bank will lend someone $200k for the ticket to go to Mars on the offchance they might be a successful pizza restaraunteur.
But like I said, if you're (e.g.) him and you buy your own hype…
(His grandkids' lifetimes are another question entirely. Things are changing too fast).
While I believe we’re in a slow takeoff, I believe we are in a takeoff. The important question to my mind is whether AGI comes before systemic societal collapse due to climate change. I think it does, and my tin foil hat grows a wider brim with each passing day. I hope I’m wrong!
My expectation is that a lot of social breakdown happens with AI that's not quite capable of fully replacing human labour. A lot of angry unemployed people, or a lot of people who suddenly find they're unable to compete with data centres for electricity and can no longer afford to keep their freezer frozen, groups like that may not be able to pull of a Butlerian Jihad, but they're absolutely relevant to the timelines, and I think they happen before fully-automated security bots that are worth bothering to install.
As you may infer from my use of the word "hype", I do not think we are close to such generality at a high enough quality level to actually do this.