Heard an interesting take on the unicorn state of play this weekend on Barry Ritholz's Masters in Business podcast. William Janeway (Warburg Pincus) thinks there is definitely a unicorn bubble going on, but just like the railroad bubble in the 1800's and the automobile bubble in the early 1900's and the PC bubble in the late '70s and early '80s and the Internet bubble in the '90s it will end with a lot of people losing money, quite a few making money, and a lot of companies going out of business, but with a lot of survivors and a lot of infrastructure that will fuel ongoing progress, and that this is a good thing on balance. His belief is that equity bubbles are a lot less dangerous than credit-fueled bubbles like the housing bubbles of the '00s.