If total stock balance > 100 folds of annual expense

Then you don't worry about stock market crash. Because it will come back eventually. Maybe a couple of years, maybe several years. But you have enough money for 50 years even the maket drops 50%. you want to have a bigger balance/return in long term.

however, if the stock balance is only 10x of annual expense. You will start to worry when it drops to half.

there are two key factors when it comes to overcome a bear market (1) do you have enough time to wait (mainly your age) (2) do you have enough money to wait (remaining balance after living expense)