[dsheets]

I agree with you. The island simplification came later. If the economy is broken, gold is not a good investment. This doesn’t change the fact that it is also non-extractive of future labor, though, which was the purpose of the thought experiment.

The problem with productive assets or non-inert commodities in this thought experiment is that they are much more dynamic — inert commodity prices are much easier to reason about.

You are fundamentally correct about capital accumulation, though. If you want future value, you should accumulate something (dynamic or static) that is valuable in the future — extracting rents or expropriating labor via force in the future are not pro-social behaviors.