As the hype builds for the reported $1.5 trillion IPO of Elon Musk’s SpaceX later this year, there will be plenty of critics who argue the company’s marketing has more hot air than one of its rockets. It has been claimed by some that the IPO will be worth more than the top seven companies currently listed on the London Stock Exchange – including century-old giants such as Shell, HSBC and AstraZeneca – combined. And yes, sure, there is probably an element of wishful thinking in these reports, as there often is with Musk. But SpaceX also has the potential...