I keep relatively little cash, mostly just enough to cover bills for several months. There are many ways of having cash available in a downturn, beyond holding cash, with their own tradeoffs. Borrowing against assets doesn't always work because lenders can and do freeze lending to manage their risk during a major downturn. Bonds used to be a good place for uncorrelated liquidity during a stock downturn but this is no longer the case and they are essentially cash-equivalent at this point because they have no yield; I've seen literature in recent years suggesting bonds as they exist today serve no purpose in a well-designed portfolio because you manage risk better with options.

In current market conditions, hedging (e.g. buying put options) is one of the more effective ways to have cash available in a downturn while still being invested in long-term upside. If the market crashes, these hedges become worth a lot of money, which you can then sell and invest the proceeds in whatever you wish. Hedging isn't free, so if a crash never happens it eats into your returns for the year -- it is an insurance policy and you have to pay a premium. On the other hand, if the market has a great year the gains will greatly outweigh the losses from hedging. The worst case outcome is if the market is completely flat -- no gains but you still pay the hedging costs.

FWIW, I tend to be ~100% in individual equities, even for money I intend to use soon. Managing stock price volatility and cash flow does not require exiting stocks.