I am in charge of social media at a CareerVillage. So yes it can be a job if you know what you are doing. The problem with doing social media as a career is that literally EVERYONE knows how to use it. So you have to bring some extra things to the table. You will need to have some graphic designing skills and strong writing skills to develop content for your employer. It is easier to find jobs in social media for a start up, a non profit, or small business. They often have smaller teams and often they don't have someone dedicated 100% to social media. Professionally, it is a an awesome tool for communicating about events, services, products, or news.
Now onto the "bad" side of social media. It can take away a lot of your time. I often find myself scrolling through instagram and facebook and then I realize, "Oh I just wasted an hr or two." Social media can be addicting so it is always good to find the right balance of time you spend in the digital world and the real world.
It is totally ok to use social media for personal uses. I personally am a big supporter of social media. When older people say it's useless I will often argue that they are wrong and they don't know what they are talking about ( which is true they don't haha.) When it come down to it, social media keeps us connected. We are able to learn about things that are going on in the world, society, and our own community in a matter of seconds. If you sit back and think about that, what we are able to do with social media is really amazing. I hope this is helpful, feel free to ask me any additional questions! :)