I'd think facebook is scsry for me because i myself am a heavy user of it and almost all my apps are synced up to it so I don't need to enter my passwords all the time. That being said, there is alot of pertinent dta there about me. Although this data in itself is not important, but combined with others, it's dangerous.
You better watch out bro! You are being monitored and your data is being collected across board. 
Just kidding though! However, it is still something you always have to take into consideration when it comes to data and with some of the news we have heard in the past about Facebook selling the user's data to highest bidders which to me is highly unethical. Sure, we can say we share data everywhere and as long as we are on the internet, data are prone to be leaked sometimes, if it gets into the wrong hands, but whichever way, in this case, what can we really do about it?
We can simply do nothing about it. Those data aren't really concerning. The data social media are selling are things like how much teenagers are spending time online or what are the things do they like. Those are data that are collected by your activity by using social media. It's all for marketing so companies would know if what they are selling are going to hit the market or not. If your concerns are your whereabouts, you still have control over your fingers and what you post on social media so pretty much you can just NOT post where you are instead. People like using the hashtag #atm which is quite dangerous in most cases since you might have a stalker especially if you are a girl.
At the end of the day, we really can't do anything about it since social media has become a normal thing in our society. If you don't have a social media, people see you as a hermit or a weirdo. We will always use social media and the key is to not post everything. Be mindful of what you put out there because what you put out on the Internet is there forever.