Every time you've swiped the screen on a new iPhone or entered keystrokes on your Galaxy, you may have helped make Yeung is the founder and chief executive of Hong Kong-based Biel Crystal Manufactory Ltd., one of the biggest suppliers of cover glass to Samsung Electronics Co., the world's two leading smartphone manufacturers. His control of the closely held business and ability to fend off competitors such as publicly traded Lens Technology Co., has given Yeung a net worth of $7.2 billion, according to the "In the field of cover glass, Biel has always been the market leader," said Terry Yu, a Shanghai-based analyst at IHS Technology.