Before revision:  In multiplicative growth, ergodicity is broken in such a way that fluctuations have a net-negative effect on the time-average growth rate , although they have no effect on the growth rate of the ensemble average. Pooling and sharing resources reduces fluctuations, which leaves ensemble averages unchanged but -- contrary to common perception -- increases the time-average growth rate for each cooperator .
After revision:  In multiplicative growth, ergodicity is broken in such a way that fluctuations have a net-negative effect on the time-average growth rate , although they have no effect on the growth rate of their expectation value. This is an example of non-ergodicity. By reducing the amplitude of fluctuations, pooling and sharing increases the long-time growth rate for each cooperator .