I think if you look at the incentives in that situation it's very understandable to not speak out. If you're a good employee working at Riot and you have a problem with the culture you have two options: Speak out or leave. If you speak out it can be incredibly damaging, you'll almost certainly destroy your career at riot because you'll be actively attacking people you work with. You stand a good chance of getting a reputation in the industry. The likelihood of changing the culture is microscopic - especially if you find out it's the CEO providing the lead in this behaviour. And if you succeed? Your career at Riot is still probably damaged, Riot's culture will be like any of the many other companies you could work at. During the time you're fighting for that change it's likely to be incredibly emotionally draining and you're bound to lose some friends.

If you leave, you have literally none of those downsides, you've still got a good career and you can go off to one of the many other companies that are just as successful without those downsides.

So to speak up you need to be incredibly principled AND you have to have some very deep stake in making THIS particular multinational corporation better. I think it makes perfect sense not to speak out for the vast majority of people.