Answer:
Because if they don't have wealth they won't be able to buy their supplies and hire crewmen. They wouldn't be able to get ships and boats.
Factors leading to the expansion of the Texas frontier. Texas Frontier Timeline, 1866-1875 · Texas Frontier Timeline, 1876-1882 · U.S. Army on the Texas Frontier · Windmills · "Forting up" on the West Texas Frontier.
I think this would be antibiotics