If one or more major customers fail, that frequently causes problems for their bank and can negatively impact all bank customers. Banks have developed plans to maintain increased currency volume. Banking is confident of minimal Y2K disruptions, so banks are planning to handle the return inflow of larger quantities of currency early in 2000. Cash is not insured by most home owners insurance. Cash doesn't earn interest.
Bank deposits do.
Cash poses risk of theft, fraud or other loss. A bank's thick vault door is more protection than a consumer's mattress or tin can. See recent Y2K fraud scams, below. These are wise steps at any time, but especially now re Y2K. Keep good records of all your banking transactions, especially late in 1999 and until you get several bank statements in 2000. Save your transaction receipts and check them against your bank statements.