I think it is a mistake to be 0% invested, I am about 70% invested and will probably reduce that to about 50% due to covered calls hitting.
Even if I was very sure a correction was coming I would be 10% invested.
I would probably only need a 5% correction to get up to 90% invested.
Of course 100% invested is not a limit I am willing to go to 300% invested using leverage, of course not at the moment.
I think we are at the beginning of a massive multi-year economic depression starting with a hyperdeflation. In a depression there's the saying "Cash is king". So I basically hold only the 3 forms of cash (USD, Gold, BTC) + 1 risky investment (Hive).