Is there really something useful for 500 developers to do that the top 50 of them couldn't have done?
I've always assumed (since I don't understand it) that it's just a momentum thing. Did you ever consider keeping Airbnb under 100 employees? Would your investors have freaked at that idea? Would it have hurt your growth?
Let's not forget about cars, trucks, bikes, why not start competing with zipcar, Hertz, Budget, Enterprise? Sometimes you need a car when you travel, right?
Commercial REITs are getting into the rental space as well, they might have some sort of deal lined up with large players. Let's also not forget about coworking spaces for when you want to get work done on the road...
Airbnb for play, airbnb for work, airbnb for commercial real estate, airbnb for wheels, airbnb for...
A company's revenue per employee is a common benchmark, and is usually around $600K-$1MM or so for successful companies at or near scale, up to $2.2MM for outliers like Apple(1). A company cannot grow to $100MM revenue and higher without having a large number of employees just to manage those revenue streams, partnerships, contracts, and support issues.
I should add that Instagram had ~13 employees, not two. That is a very low number, but mobile apps are easier to scale, support-wise, than web apps – users are just less likely to bug you, especially with a free app.
(1) Comparing Google, Microsoft, Apple and Amazon's Revenue per Employee: http://www.wolframalpha.com/input/?i=revenue+per+employee+ap...
So honestly, I'm curious---what is AirBnB going to do with ~1000 developers. Facebook expanded their headcount and created a whole suite of products glomped onto their original vision. I'd like to know if AirBnB intends the same and if so what are their plans.
Ofcourse, they have no obligation to blab about them early.