I'd say this is effectively the opposite of Malthus, since too much food (or rather too many products in general) kills jobs, and more fundamentally, kills the ability to earn rent from investments.

I don’t think that’s how economies work, but I accept I am likely to have a very flawed understanding of the field.

More people means more potential consumers, surely? So the only way there could be “too many people” is if the market is dominated by goods which have a high one-off cost and trivial per-unit costs, such as software or other digital goods?