A lot of human knowledge cannot be written down and has to be passed on person to person. There isn't enough bandwidth in a book to actually convey a lot of it.
Machining is one instance of this. You basically have to have somebody show you how to do some of it. Same thing with forging.
The difference between the most detailed written instructions and apprenticeship / personal instruction is instant expert feedback. Skills transfer can happen much faster when the loop is closed.
The examples you cited can be written down and they don't have to be taught in person. You could instruct somebody to do these without being present in person. I'm sure there are reasons that's not the way it's taught primarily, but you've not convinced me it's fundamentally impossible.
You don't need a complex example. Your first language is something that can only be taught by people who are alive. Even if there is a comprehensive textbook that teaches all languages you still have to learn your first language to read the book.
We’re perfectly capable of building electronics that can run for many tens of years without issue… it’s just that such things don’t get built because that’s not profitable for manufacturers. If an organization like NASA puts in an order for computers or handheld devices specifically designed to not break for long stretches of time, it wouldn’t be a problem to fulfill said order.
You mention billionaires and then list off new money entrepreneurs. Don’t conflate the two. There are jobless people born into billion dollar family dynasties that do absolutely nothing for humanity. They hide and live out their lives entirely for them.
What are _you_ doing to leave a long-lasting meaningful impact? Billionaires are people too, just with more money. Having money doesn't make you "just ego".
Machining is one instance of this. You basically have to have somebody show you how to do some of it. Same thing with forging.
(At least in my experience)