President Donald Trump's fortune may be down a billion, according to the latest Forbes Rich List, but there are plenty of other billionaires who have raked it in over the past year. From the luxury goods magnate who boosted his fortune by $7.5 billion (£5.8bn) to the online shopping mogul who made an eye-watering $3.2 million (£2.5bn) an hour, here are the world's highest-gainers.