Is 9c misplaced? 'Provide information that is useful in and of itself. This includes journalism and creative writing'.
The author has already listed knowledge of how to do any of the other mechanisms more efficiently and effectively (9a).
In what sense is non-instrumental knowledge a fundamental source of wealth? It might be exchanged for wealth, but it is not a form of wealth itself. It is a different paradigm of activity. The author's use of the adjective 'useful' here is surely a misnomer, too.
It's also notable that one of the fundamental forms of wealth accumulation historically - different ways of securing and organising the labour of other humans - is excluded from the list.
Wonderful piece by Ron Garret. See also his Wealth-production mechanisms: a followup post:
http://blog.rongarret.info/2009/10/wealth-production-mechani...
The book "Personal MBA" by Josh Kaufman also covers this in good detail: https://personalmba.com/12-standard-forms-of-value/
> Bonus question: what did the U.S. give to China in exchange for its china?)
Gold.
Additional comments from about a decade ago: https://news.ycombinator.com/item?id=873125