Blockchain networks and Web3 platforms represent distributed systems that are utilized more and more to share data safely and to code decentralized applications. Nevertheless, such systems are frequently attacked with the Sybil nodes, collusion, bribery and reward manipulation, the latter of which cannot be entirely avoided by the conventional cryptographic or consensus-only approaches. In order to deal with these, the current paper introduces a Multi-Layer Crypto-Economic Defense Framework in which cryptographic security, trusted consensus, regulations of behavior based on incentives, and real-time surveillance are integrated into one solid framework. The framework comprises of five layers namely Network and Identity, Cryptographic Security, Consensus and Reliability, Crypto- Economic Incentives and Monitoring and Governance. All these layers are combined to guarantee the safety of node identity, encrypted communications, validated block trust, equitable rewards and penalties, and automatic reporting of bad actors. Experimental findings on the use of a simulated distributed network with a maximum of 2000 nodes indicate that the proposed system can enhance transaction throughput by up to 75 percent, over 94 percent accurate at detecting advanced attacks, and can provide economic stability throughout the network. In general, the system shows that economic-cryptographic co-design can provide a solution in the next-generation distributed systems by establishing a more secure, scalable and resilient base. It is a multi-layer solution that enhances both technical and economical protection and a viable solution to contemporary decentralized infrastructure