That's a very long winded way of objecting to Yvain's model of the American economy as largely zero-sum games (eg. poker). If the village is a static economy with fixed output... Then sure, modafinil is fairly questionable. But this story is a way of asserting it is not with hypothetical examples.

Of course, it's not obvious that iodine is necessarily a good thing. Malthusian models come to mind: if intelligence has no effect on subsistence wage, then it can have no effect on per capita wealth and so any effects are redistributional, and if you want to argue it's a good thing you need to appeal to extra things like quality of life... which actually probably would affect subsistence wage since now you don't need so much wages, your quality of life has been improved. Intelligence might come with a one-time increase in wealth, which of course simply causes the population to expand and that the temporarily-increased-per-capita-wealth will eventually fall back down to equilibrium as people reproduce more. :)

"It was a bit sloppy essay of Yvain - cool idea, kinda weak execution" is what I might say if he had posted it to Main instead of his blog.