SVB's failure means that anything over $250k that a startup had there is not currently accessible. They'll probably be made whole in a couple of months by FDIC, but payroll, along with rent and the cloud bill won't wait and can't be paid via IOUs.
I never heard that before. The rich keep their money in investments.
For your explained meaning, it is in depositor's individual interest to remove their money. Get cash or t-bills. Also get a credit union account where they work for the members.