What is the biggest concern regarding the rapid spread of fake news online ?

What is the biggest concern regarding the rapid spread of fake news online ? How does social media facilitate the rapid spread of fake news? Why do you think it is so easy for us to spread fake news, spam, and misinformation via these tools today? How might we, the users, and social media sites work together to combat this issue?
Lee, T. B. Facebook’s Fake News Problem Explained http://www.vox.com/new-money/2016/11/16/13637310/facebook-fake-news-explained (Links to an external site.)Karlova, N. A., & Fisher, K. E. (2013). Plz RT”: A social diffusion model of misinformation and disinformation for understanding human information behaviour. Inform Res, 18(1), 1-17.Action