Is social media worth it?

After spending time in class focusing on social media platforms and doing blogging and similar things, I am wondering if any of this stuff really affects anyone? Personally, I feel that all of these platforms and websites are pretty stupid except for the rare occasion. I have heard many horror stories with Facebook and employers and schools, sexual predators on Myspace and now drama everyday with some stupid comment that athletes or movie stars make on Twitter. Do the benefits ever outweigh the problems that these services cause?