The number of Cancerians on the rich list has risen by two since 2017, with seven billionaires belonging to this star sign. Some of the most notable include: Tesla Motors founder and CEO Elon Musk, worth $22.1 billion (£17.3bn); Heineken heiress Charlene de Carvalho-Heineken, worth $13.8 billion (£10.8bn); and Cheung Kong Holdings founder Li Ka-shing, worth $37.7 billion (£29.6bn).