Earlier quoted context omitted.
I'm intrigued by your comment that you have an advanced degree in economics. I don't, but it seems obvious to me that you're missing something (I'm happy to be corrected here!): the problem isn't the lack of consumers so much as a lack of incentive to produce. If everyone becomes an entrepreneur, compelled to be stingy and just do productive things for the fun of it, then they're still being productive, and the world…
Actually that is NOT at all what my argument is. My argument is that people can produce as much as they want, but you still need someone to consume your product. Just being productive gives you only the supply side, but what about demand, why make would make something when people do not demand it. Remember PG's rule: Make something that people want. Want is demand. You cannot make things without taken into contention…
Exactly. Perhaps a good way to view this would be to resrict the definition of supply to be only something that has a demand. So a fisherman that "supplies" rotten fish that nobody wants is not providing a supply, he is just wasting resources.
The hard part of economics is always the supply part: how can you increase supply? (Supply defined as what people want.) When productivity is below the subsistence level, increasing supply consists in just producing more food. But as productivity grows beyond the subsistence level, the challenge becomes an informational one: out of all the things you could do, what should you do to increase the total supply the most? A man who is hungry just wants more food, any food. But a man who is sated will only want certain particular kinds of food or maybe something else entirely.
This is what prices in a free market are for: they provide information about what the economy needs the most. In an economy of hungry people, any kind of food will sell. But as the population gets sated, prices will tell producers that common-place food is not needed anymore and that they should produce something else.