I've read Permanent Portfolio and feel skeptical about their diversification strategy. Personally, I feel this is highly outdated methodology on risk management. The only redeeming aspect I see if diversification through "rebalancing".
Today with the advent of multiple asset classes for the retail investor especially in real-estate, and crowd-funding real-estate P2P loans, mortgage notes etc, offers tremendous levels of diversification that are de-correlate from recessions.
Heck! Even bitcoin is an asset class. It can be used to hedge against an hacking incident that could tank the valuation of your portfolio companies. Case in point, I trade MDLZ actively. They were hacked in May'17. Company lost 5% of their market cap so hedged with 1.75 BTC at 2000. Hindsight, should've bought 10 BTC's instead.
Actually, there's a code/software behind bitcoin. If it gets hacked, could go to (near) 0 pretty quick. The same is true for other cryptos as well.
