Well the first thing to note is that ~90% of all media news is negative. That’s not new or unique to social media though. News has traditionally been negative way before smartphones were around. What is new though is we now have the ability to better curate what information we see and read.  

In the past you would turn on your TV and put on the evening news and watch whatever they laid out for you. You now however have the ability to decide who to follow online and choose what you read and/or see. There is of course good and bad to this. If you choose to follow lots of accounts that post sensational stories or misinformation, you could be getting led down the wrong path. If however, you follow reputable accounts you can get a more accurate sense of the world around you.