Personally I'm happy when good things are happening for family, friends and other people, but depending on my mood it can also trigger feelings of FOMO/anxiety (why isn't that happening for me, what am I missing, etc.). My guess is depending on the person and their current state that falling into a pattern of focussing on the latter rather then the former is easier when using social media. Which can then be a bit of a vicious cycle because cutting yourself off from social media may also mean you miss events that you could have participated in