The evolution of the Quantified Self (QS) movement from 2010 to 2025 represents one of the most profound shifts in the history of personal health, technology, and sociology. What began as a fringe subculture of "bio-hackers" and data enthusiasts in the San Francisco Bay Area has metastasised into a global infrastructure for predictive healthcare, underpinning a multi-billion-dollar market for wearable technology, remote patient monitoring (RPM), and personalised medicine.