I can't think of anything more useless and stupid than cave farming. Seriously, how the hell do you expect to plant caves, much less grow them?
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#Destiny
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Mercury actually has a vast economy due to farming caves. Low managing costs, endless surplus of unused ammo, gear that is seemingly left unused or broken in the caves but easily repairable. There is actually a gunsmith from mercury in the last city that sells these to new guardians at 70% profit margins. All in all a win win.