This session will analyze what cryptocurrency design aspects threaten to destabilize the marketplace and expose systems to hostile take-overs, and will describe why the reliance on PoW contributes heavily to a lack of robustness and how PoS based solutions can help strengthen systems. With greater robustness and an associated growth of the marketplace comes benefits, such as high-speed transaction support.Learning Objectives:1: Understand stability risks of cryptocurrencies.2: Learn to analyze robustness risks, using proofs of work as case study.3: Analyze the potential benefits of a shift towards proof of space.Pre-Requisites:General familiarity with how cryptocurrencies are constructed and work.