Health tech ‘unicorns’ are rare beasts leading to Silicone Valley to be a bit sneery about the healthcare market. However, is that scorn justified and why are unicorns – start-up valuations exceeding £1 billion – so hard to achieve? Here I discuss the topic at Web Summit 2017 with Zach Weinberg, co-founder, president and COO, of Flatiron Health, one of those mythical unicorns, to find out more.