Though Nostromo is obsessed with growing "rich," it remains true that
every character uses the San Tomé silver merely as a means to an end. In
this case Nostromo's real goal is independence -- security from betrayal.
Note that his denunciations of the rich now include the poor; the effect is to
widen the scope of possible betrayers to all mankind, and clarify the allegory
in which the People, having rejected their exploitation, will not rest until the
entire world is free from the prospect of it.