When Marcus Butler told his parents of his plan to devote himself to his YouTube channel, he was earning just “tens of pounds.” That was eight years ago, when the excited 18-year-old had just returned from VidCon, the annual online video extravaganza in Los Angeles, where he met vloggers who had bought houses with their earnings. “There was something material that showed there was potential in it,” he says. Having traveled to L.A.