Why do our friends' friends have so much more interesting lives than we do?

they don't. it's all a lie

Because you only hear the anecdotes and don't know their day to day.

Everyone is always facing at least one problem. Not because they don't show it or talk about it, would mean their life is more interesting than our own. It's usally all a facade. The grass is never greener on the other side of the street (or how do they say that in English :) ) .

Because they weren't forced to go to a certain college

Because social media shows us the pretty corners they allow us to see. We don't see all of the monotony and despair.

Great question