This incident is the first one I've felt this strongly about. There have been many others, but even Cambridge Analytica, to use that example, was just taking information that was semi-public (your likes and interests that all your friends could see), and abusing that information. But that was information that I never mentally compartmentalized as private. Sure the scale and method of abuse was unprecedented, but I also don't blame facebook as much as many people did for not really knowing the extent of how that data could be abused. I also believe that fake news spreading on facebook was a novel-at-the-time phenomenon who's impact was hard to detect until after the damage was done.

My private messages are a whole different category of private. Facebook had a phenomenal engineering team and I put the same trust in them that I put in google for my email. A hack is still possible, but it's the highest level of trust that I can have in a service that I can't control (sure things like Signal exist, but 99% of my friends don't use it, so there's a tradeoff). So this particular incident, and the dismissiveness of the response, is my dealbreaker