Data is the defining resource of the 21st century, but the question of who owns, controls, and benefits from it has become strangely opaque. This article revisits the idea of digital sovereignty in light of three technological frontiers: the Internet of Things, Brain-Computer Interfaces, AI and its acceleration through quantum computing. It traces how regulatory retreat and public disengagement have opened the door to unprecedented forms of data extraction, including from the human brain itself. The fight for data rights may well be the defining democratic struggle of our digital future. This article calls for a renewed public conversation about data as the foundation of democratic self-determination.