I think the problem with kids is not so much social media, gaming or anything technology offers. It's parenting.
It seems to me that a lot of parents just dump their kids in front of the tablet/TV/console and do their own thing, with limited interaction with the kid. Rather than just label me as some liberal fool who believes games encourage violence, please bear in mind I don't actually believe that. I believe that games can cause violence *if* the perpetrator has not been adequately taught by their parents not to use violence. In short, I believe that if your parents just dump you in front of (say) the latest Call of Duty or GTA game rather than actually teach you stuff, you are more likely to turn to violence.
Similarly, if kids are allowed unrestricted access to any social network, they are likely to learn their behavior from that network. All well and good if their social media friends are good and decent people, but if they are not. I think at the very least, a good parent should be teaching their kids to be careful what they type, and reveal, especially when communicating with people they don't know in real life, and be aware that what they post may be accessible to a lot more people than they intend it to.