Regulating banks is important for a stable economy. If banks fail, it can cause a financial crisis. One common crisis is when people rush to withdraw money from a bank because they don't trust it anymore. This can happen if the bank loses a lot of money or if people think it's not financially strong. Rules about how much money banks must keep can help prevent this. If a bank is in trouble, it might take bigger risks to try to survive. So, it's important for all banks to follow these rules to protect everyone's money.