I used to be an engineer at Airbnb. It's not, in fact, the case that people are doing "unpaid overtime". My favorite example of this: there are a great number of people who work there who were MORE than willing to take a free Saturday/Sunday and host their OWN hackathon with their work-friends when the company-supported dates proved inconvienient for a lot of us. While it's true that a lot of the projects were company focused, a great deal were purely "stupid shit nobody needs and general shenanigans" projects. It's not the kind of place where people feel forced into working in a silly way. It's an awesome place full of rather clever people.

/endrant