I left FB when somebody on HN leaked they were feeding data straight to some military intelligence agency pipeline. I lost many acquaintances because of it but I saved a huge amount of time and completed two graduate degrees after.
The HN search doesn't show anything like that. I wish I saved the link somewhere. It was a long time ago but IIRC they had some bug that browser was directly contacting the agency instead of doing it via a backend or redirects so people monitoring their own online traffic could see the target servers directly.
