Why can't the central bank control the money supply completely?

The central bank cannot control the money supply completely because it relies on financial institutions and the public's behavior in the economy. For instance, when banks lend money, they create deposits, which expands the money supply beyond the central bank's direct influence. Additionally, factors like consumer confidence, demand for loans, and the velocity of money can vary, affecting the overall money supply in unpredictable ways. These dynamics make it challenging for central banks to exert total control.