Hundreds of property investors and wannabes fill a stuffy conference room in Cau Giay, a working-class suburb in Hanoi. “I love property!” they stand up and yell at one another with high fives. It is an exercise prompted by the coach, Welsh multi-millionaire property investor Kevin Green, to break the monotony of sitting down all day. “Yes, yes, yes,” they shout at this three-day real...