Their tents prospering represents the robbers prospering in their tents. Alternate translation: "Robbers live in prosperity in their own tents" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Here "their own hands" is a metonym for strength, and "their gods" is a metaphor for their pride. Alternate translation: "they are extremely proud of their own abilities" (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-metaphor]])