True enough, but not what I was referring to.

ETA: I'm referring to the following (along with some of the other studies linked by gwern):

cognitive skills—intelligence quotient scores, math skills, and the like—have only a modest influence on individual wages, but are strongly correlated with national outcomes. Is this largely due to human capital spillovers? This paper argues that the answer is yes. It presents four different channels through which intelligence may matter more for nations than for individuals: (i) intelligence is associated with patience and hence higher savings rates; (ii) intelligence causes cooperation; (iii) higher group intelligence opens the door to using fragile, high-value production technologies; and (iv) intelligence is associated with supporting market-oriented policies.

JoshuaZ is referring to something hugely more generic and obvious (revolutionary geniuses and cumulative knowledge vs significantly above average IQ workers in contemporary economies).

It's true, but a weird use of "free-riding". In that sense you could also say that every child is free-riding on its parents' investment in raising it.

Perhaps the rich

I don't know if that's serious or snark, but I don't think it's necessarily the rich. For instance, the management class could absorb the positive externalities of their more intelligent and less socially adept subordinates while only being marginally richer. So, as a whole if you could say the management class produces no to few benefits themselves, and yet takes a huge chunk of economic wealth roughly the size of what you'd expect from the positive externalities from intelligence, then you could potentially make some interesting conclusions.

ETA: I'm using this as an example of the kind of thing I'm talking about, and I'm not supporting it as a conclusion or even a hypothesis.