> while their education did not ensure their economic success, it played a role.

That half concedes the original opposing point.

> think of the return to education as stochastic

To say that the effect of education is stochastic means it includes some either purely random factor, or something else not understood or not considered -- i.e. the thing having a big effect is not the basic factor of education but something else. Well, that really does seem to concede the original opposing point.