The barriers to entry in their fields are huge. - As you mentioned, in anything social, the network effects are immense. - In anything where inputs are fuzzy a

The barriers to entry in their fields are huge. - As you mentioned, in anything social, the network effects are immense. - In anything where inputs are fuzzy and machine learning is required, the biggest data corpus wins (language recognition, image recognition, video recognition, translation, self-driving cars, payment fraud detection, etc etc). Open training corpuses won't ever be as extensive or fast to access as the proprietary hoards that the Big 5 US tech giants or the Big 4 Chinese giants have. - Given their value-add in terms of phone OSs+cloud storage+apps+mapping, Apple/Google/Facebook/MS get data that anyone else will never get. 24/7 location updates PLUS your full contact list PLUS most of your photos with pre-tagged content - enables targeting and monetisation of a vast scale and scope. Basically, the antitrust issues are already so huge that I would not be willing to bet on firms outside the Big 5 in any profitable area that touches tech - whether it is self-driving taxis, cord-cutting smart TVs, home automation - and probably also online payments eventually. They will not just eat Uber's lunch and Netflix's and Spotify's, but eventually also that of the cable-cos and of the VISAs and MasterCards -- just like Tencent and Alibaba are demonstrating on the Chinese market.