Thoreau was talking about his townspeople that were inheriting or buying unproductive farms. He also wrote a lot about the condition of the Irish immigrants who were clearing bogs and laying in the railroads.
Thoreau was writing about 15 years after the invention and commercialization of the McCormick Reaper, an implement that was perfect for the rolling plains of the prairie states, but ill-suited for the rocky, mountainous and forested land of New England. The farmers in and around Concord were unable to compete with the Midwest, with the railroads ensuring that western crops could swiftly reach Eastern markets.
The result was too often debt and penury for the small-time landowners, and exploitation and abjection for the Irish laborers. Thoreau favored self-sufficiency as a mode of living, and abundant leisure time as its greatest fruit, and felt that others could profit by his example.
But of course he was Harvard educated, unmarried with no children, had the opportunity to stay with family, etc.