How? It’s pretty much the point and purpose of civilisation, to say nothing of industrialisation.
> we don't put enough economic value on people making things themselves.
The invisible hand is a middle finger. Always has been.
> How? It’s pretty much the point and purpose of civilisation, to say nothing of industrialisation.
Civilization isn't necessary for this to be true. It is even true in small scale societies. You can observe this whenever they get cutoff from each other: they end up technologically regressing. It is more expensive to do everything themselves, so they end up losing access to technologies.
The world where this was last true was when the common ancestor of us and neanderthals were still around.
When you get so good at making something that it takes you 0.1-0.5 of the time it takes someone less experienced/skilled, the cost of your labor becomes an diminishingly small part of the overall cost. That makes it ever more difficult for the unskilled person to ever be able to make it "cheaper", even if they consider their time to be free.