Disabled all that social media shit way back. Didn't look back once. People who mattered reached out, those who didn't, didn't. Life moved on. So much for all their "psychological influence".
That said, I have other more tolerable addictions (like reddit).
On the flip side, shortly after I graduated I realized it was my default "thing to do" online (i.e. when I open my browser it was muscle memory to type in facebook.com). Yet when I opened it up I cared less and less about what I would actually see. Anything worthwhile I would have gotten a text/call about, everything else was just attention-grabbing noise.
After I disabled my account honestly I can't say parting with it had any negative effect on my life whatsoever. Anyone who would have invited me to something on FB just sent me a message on something else, or text/called. Any friends I wanted to stay in touch with did so any way in other ways. Anyone that I lost touch with wasn't someone I was trying to stay in touch with in the first place.
It's amazing how often I hear people complaining about Facebook or the people they have "connections" with on there, but just not using the platform is almost a foreign concept for them at this point.
Take a look at a community like /r/fitness, and you get a lot of people recommending a lifting program that requires you purchase a book.
The worst part is, once it's been brought up enough (read: astroturfed enough), users naturally start to parrot it to fit in.