A perfectly solvent bank can still be destroyed by a bank run

Diamond and Dybvig showed mathematically that bank runs can be self-fulfilling: if enough depositors merely expect others to withdraw, rushing to withdraw first is individually rational even though the bank was fine. The 1983 model explains why deposit insurance, not just bank health, is what actually stops panics. It won the authors a share of the 2022 Nobel Prize in Economics.

— Douglas W. Diamond and Philip H. Dybvig, Bank Runs, Deposit Insurance, and Liquidity — Journal of Political Economy, 1983