In a truly decentralized world, the burden of security shifts entirely from the institution to the individual, making digital sovereignty both a profound privilege and a high-stakes technical challenge. This masterclass delves into the cutting-edge methodologies required to safeguard high-value digital assets in an era defined by increasingly sophisticated cyber threats and social engineering attacks. We move beyond basic seed phrases to explore the implementation of Multi-Party Computation (MPC), the strategic deployment of social recovery wallets, and the necessity of hardware-level encryption for long-term cold storage. By providing a definitive resource for both individual power users and Decentralized Autonomous Organizations (DAOs), this article equips readers with the mental models and technical frameworks necessary to navigate an adversarial digital landscape without ever compromising on the core principles of decentralization.