SEOUL, July 10 : When South Korean billionaire Chey Tae-won attends a bell-ringing ceremony on Friday for SK Hynix's $26.5 billion Nasdaq listing, it will mark the ultimate payoff of a bet many once considered risky: buying a loss-making chipmaker that has since become an AI powerhouse.SK Group's 2012 acquisition of Hynix was viewed as problematic even within the business conglomerate: Memory chips are cyclical and capital-intensive, and the company was losing money while trailing Samsung Electronics in market share and technology.But under Chey, seeking an edge over Samsung, SK Hynix has spent more than a decade betting on high-bandwidth memory (HBM) chips, at the time a niche technology. The wager paid off as HBM became a critical component in Nvidia's AI accelerators, helping SK Hynix e