(Bloomberg) -- On a sweat-laced evening in June, while much of Hong Kong dug into supper, two dozen students snaked their way past ginseng dispensaries and tailor shops to the third floor of an office tower to be schooled in finance’s hottest trend.The cohort was a white-collar jumble - some were private bankers with gym bags, others primly-dressed accountants. They’d come to study the ABCs of family offices - firms dedicated to managing enormous, secretive pools of generational wealth: from the