I don't know - I still think that you can replace twitter in a weekend. You just need a couple of markov chain outrage bots shouting at each other, porn scraping bot and a bare metal web server that can process couple of million requests per second.

Jokes aside - the biggest error this software developer makes is not realizing that software is not the crtitcal part of AirBNB success. It is the thousand manyears of boots in streets promoting the app and getting people onboard.