All currencies need some way to control supply and enforce various security properties to prevent cheating. In fiat currencies, organizations like the central banks control the supply of money and add anti‐counterfeiting features to physical currencies. These security features raise the bar for cheaters, but they don’t make money impossible to counterfeit. Ultimately, law enforcement is necessary for stopping people from breaking the rules of the system.
Cryptocurrencies too have security measures that prevent people from tampering with the state of the system, and from equivocating; which is, making mutually inconsistent statements to different people. For instance, if Timi convinces Ebi that she paid him X coin, she should not be able to convince Eze that she paid him that same amount. But unlike fiat currencies, the security measures of cryptocurrencies are enforced purely technologically and without relying on a central authority.