In a post on the social media platform he owns, Elon Musk recently lamented: “Whoever said ‘money can’t buy happiness’ really knew what they were talking about.” Now the world’s richest person can put that maxim to an even bigger test as he adds a new title: world’s first trillionaire. Shares of SpaceX rose 19 per cent on Friday to US$160.95 each in their first day of trading, vaulting the value of the rocket and AI company Musk founded to US$2.2 trillion. His fortune now stands at the...