[alickz]

>But why would I? It's not like they took something from me. I am the lord of my destiny.

Envy. You can be genuinely happy for them, but then be sad that your life isn't going as well. I think this compounded by the idea that a lot of people don't feel like the lords of their destiny, more leaves in a river unable to fight the currents.

Which of course adds to the stress of "Why can't I be better and more like [friend]?". Which may or may not lead to productive self-reflection (more likely not in my experience)

>And how is it in any way different from the same people telling me this stuff at a pub? I don't think social media has anything to do with this.

Scale, I would imagine. If it was one or two friends I think it's easier to rationalise, but when you see friends-of-friends and celebrities "living their best life", every day, while you struggle to keep your head above water, it takes a toll.