What Is the Role of a “Security Budget” in Maintaining the Long-Term Viability of a Cryptocurrency?

The security budget is the total amount spent on securing the blockchain, primarily the block reward (subsidy plus transaction fees). Its role is to incentivize miners or validators to provide sufficient hash rate or stake to prevent attacks like double-spending and 51% attacks.

As the block subsidy diminishes (due to halving), the security budget must be increasingly covered by transaction fees to maintain the network's long-term viability and prevent the chain from becoming economically insecure.