Farfetch is a platform. McCarthy explains how the market values a platform using a bottoms up customer-based analysis, which recognizes that the business is creating annuity value. Always remember in doing a valuation: "Cash rules everything around me" (CREAM)!
"The net present value of all future revenue a new Farfetch customer generates for the firm is an eye-popping ~$4K. Farfetch is spending about ~$100 for each new customer it acquires." Trying to value a platform with a P/E ratio is like using milk as an engine lubricant. 
A platform with high gross margins makes life running a business better. "Farfetch’s gross margin remains constant at its current level of 51.4%." What other platform has high NPV per customer? 25iq.com/2017/07/15/ama…
A key question in valuing any platform is TAM. How big is the Farfetch total addressable market? 25iq.com/2016/10/22/a-d… Farfetch will eventually hit an "invisible asymptote." Not every market is as big as AMZN Prime. Some platforms have a small TAM. Some don't. It depends.
