The message is a lot better than what Amodei and Altman are pushing at least.
All Zuck is doing is reverting to the mean, which is fine for him to do because his company has no AI strategy and is not competitive with the others. IF Meta succeeds in AI, it will be because they don't need it to be profitable, it can be free and saccharine and toxically positive so long as it makes it slightly harder for people to stop watching their ads.
Unlike you, I don't doubt that they believe the message of doom, risk to humanity. They're also not alone, there's a meaningful set of influential people who also think along those lines and are public about it.