Any kind of scarce assets really -- just not currency afaict.

re: self-sufficiency, you want to hedge against all manners of problems that can break out when a developed country goes through a hard period.

• non-dependence on civil unrest second order effects like worker strikes (e.g truckers, etc), not being in a huge city where crime can really go up
• possibly remote job to allow for relocation if shit hits the fan
• electricity backup in case of high prices / grid downtime / blackouts.

etc