The debate over Bitcoin's 21 million supply cap has reignited following a BlackRock video suggesting the cap isn't guaranteed. Bitcoin's fixed supply is a key feature, but BlackRock's disclaimer hints at potential changes, sparking controversy. Critics argue that altering the cap could undermine Bitcoin's scarcity value. While technically possible through a community consensus and hard fork, many believe such a change would create a new entity, not Bitcoin as originally defined by Satoshi Nakamoto. The discussion highlights ongoing tensions between Bitcoin's foundational principles and evolving market dynamics.