Theranos

Theranos is the most overhyped flop in tech history because it wasn't just a failure—it was a $9 billion fraud built on a malfunctioning blood-testing machine. Elizabeth Holmes convinced Walgreens, Safeway, the U.S. military, and Rupert Murdoch to invest $700 million, yet the Edison device couldn't reliably run even a single one of the 200-plus tests it claimed. At its peak, Theranos was valued at $9 billion, but the technology failed repeatedly in trials. Holmes was convicted and sentenced to 11 years in federal prison, making this scandal far worse than the Samsung Galaxy Note 7's battery fires. Outperforms #4's engineering failure with outright criminal deception.