The book is great and Matt Walker is one of the leaders in the field of sleep study. There are numerous studies backing what he's written - even though there were some inaccuracies with some of the citations & ways he presented some facts, that is entirely expected in a book presenting thousands of such facts, and the author is planning on fixing all in the upcoming revised edition.
On that last part, I will confess it's unclear to me what the greater moral failing is between the 100s of thousands of elderly deaths, and lost economic growth. It comes down to how much is actually lost of course, and while I do believe what we're collectively going for is a good middle ground, I think also a lot of people don't really understand the magnitude of effects of economic growth over long periods of time.
The difference between growth of 2% and 3% are enormous 50 years down the line, and may very well translate in many more deaths due to poverty and disease, as well as a great quality of life difference for billions of people (among many other effects).
If more people are interested to sell than to buy, that will create downward pressure on the price - even if in the end for every individual trade there is both a buyer and a seller, that is a sort of "overwhelming", if you think of the buyer as a (name, bid) pair.
I am also convinced that nuts are healthy. Can you provide arguments otherwise? They are full of unsaturated fats, protein, and fiber, which, paired with an overall balanced diet, make them for sure a net positive.
To some degree, yes, but a lot knowledge can be accurately summarised, and is also both useful in general and even necessary for the good functioning & growth of society. It's not even really about knowledge, it's more about ability - to think critically, to exercise empathy, etc.
The fact that the people in the other group see it differently doesn't mean they're right though. It doesn't mean either group is right, but at the end of the day one can still take a step back and evaluate the two sources/modes of informing oneself and decide that one is good and the other is bad - with respect to what we agree it's good to optimize for (forming more accurate mental models, being well informed in general and not being deceived either by others or self, etc).