Elon Musk is not buying Twitter to make more money: he’s doing it to help humanity. In a message to advertisers last week, the world’s richest man said it was important to the future of civilisation to have a “common digital town square”. But bettering the species is going to cost money, given that Musk has paid $44bn for a social media platform to achieve that aim. The new business will carry $13bn of debt that helped fund the acquisition, and interest payments on it will need to be met – a tricky task given that Twitter generates more controversy...