Because there's a risk of being seen as "not a team-player" and a fear of losing your job as a result of it, social pressure is real in tech culture, if all developers refused to take part in the rat-race and left the office at 6 on Friday the management would have no other choice than to deal with it by _managing_ the human ressources differently, or increasing the count of developers which I will agree: is not easy when it comes to software development.
Social pressure, and the lack of interest (or even contempt) the developers have when it comes to unions mostly explains why such abuse is still seen as normal in the industry.
I'd add also the possibility of being recognized, even if only in the game end credits.
If you're young and a possibly a game enthusiast, it can move mountains.
Social pressure, and the lack of interest (or even contempt) the developers have when it comes to unions mostly explains why such abuse is still seen as normal in the industry.