Hello, is this Marta?” The man on the phone had an accent that was hard to place, but his English was clear and direct. He introduced himself as Nick. As you might expect of someone in her 80s, Marta could be a bit shaky. Had they met before? She couldn’t remember. No, Nick said. He explained that he was calling because Marta had clicked on an ad online and registered her interest in an investment scheme.

“Is this the Elon Musk thing?” Marta asked. Maybe you saw the same ads that she did last summer – seemingly showing Musk in an interview with the BBC or at a TED-talk-style event. He was peddling a new investment opportunity, which he claimed had the potential to double your wealth. In one video, Musk stared into the camera and promised that “the life you’ve long dreamed of – to build a house, to buy your dream car, to travel – it’s all possible.”

The Economist