As with the Nephites, the means to comparative wealth is commerce with other locations.
Redaction: the phrase “that they might get gain” is virtually certain to be Moroni’s emendation to the Jaredite record. This is the phrase so frequently used by his father in reference to the influences that destroyed Nephite society that its parallel appearance here, and in a similarly pejorative context, indicates that this is a concept that Moroni has absorbed from his father, and interpreted into the Jaredite record.