I think social media can just exacerbates whatever perception we already have of life, and very rarely changes it. Since we more or less control how we consume our own social media, we don't get "put on" the right path by other, or are ever forced to see things a different way for any length of time. So while the happy stay happy, the sad seem to get sadder. There's not as much positive reinforcement as negative I think, so it's very easy to get lost in the sauce.
RE: Does Social Media makes people sad? [Dtube Inspiration]