I had invested in 2007 with one of the Portfolio Management Services (PMS) of a leading Bank. The portfolio suffered a 50% loss after the 2008 crash and it was a big shocker. I admit that i did not stay invested fully as i asked the PMS to redeem some of the holdings.
That did not deter me from other investments and over a period of time through systematic investing, i built up an equity portfolio that eventually enabled me to reach financial freedom.
No one can predict such an event and it is best to stay invested. And keep cash available to enter the market when people around start panicking.