This is an interesting topic. Near-zero nominal interest rates and negative real interest rares punish savers.

Therefore, if interest rates are artificially low, it is important to diversify. In simple words, if you intend to keep $100 in cash, it makes sense to keep $25 in cash, $25 in investment grade bonds $25 in gold and $25 in equities.

The only way to maintain purchasing power in negative interest rate times is to invest in relatively risky asset classes.