> I guess I don't see how seeing people who are more successful than you on facebook could possibly be more distressing than seeing those people at work
I think you're hoping over a few categorical issues that create the social media dysthymia. It's not about seeing people who are more successful. It's not about "better" or "worse". It's about social regulation in formative egos.
From your posts you are coming off like an aspergersy male adult engineer -- I'm one of those myself, so I mean that with love -- dealing in concrete world value from the perspective of a fully formed ego not used to internalizing the external. Equating the discontent with rational motives jealousy or envy or desire, instead of judgement and personal failings implicit in habitual social comparison.
Fundamentally social media habits can create two major areas of discontent: comparing your behind-the-scenes life with other peoples highlights reels, and the comparability of the elevated personalities. To take your "boss" example: that's generally not someone I identify with deeply because my daddy wasn't as rich, and I didn't inherit the company, and blah blah blah. To our primate brains `bosses` tend to be `others` and not `us`. If that boss were your childhood buddy, OTOH, you'd have a different take on things... And that different take, and the implied reflection of being less than or worse than, that you would have with a familiar person having that role is what social media does with vacation pics and such. You're not seeing someone in another group, like someone famous, doing something fun. You're seeing someone in your group doing it, causing an implicit comparison. And this comparison is based on purpose-selected content made to project a happy image, is non-stop, asymmetrical, and always worst when you're at your lowest.
These contexts and framings are fundamental to how marketing works on us, and are a shared facet of human representation of the world around them. What you're not getting here is what a 15 yo will feel like after 3 hours a day of staring at a crappy feed that you, and most people on HN, would find deadly boring. We're also old enough and self respecting enough to avoid that crap when/if it starts to hurt. I bet HN readers are highly active online and suspiciously inactive on social media...