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.
In a transaction such as a bank, car, home loan application, our data must be copied as a requirement, and that doesn't matter. In the internet era, all social media and application owners always ask for our data. And that doesn't matter. The problem is when our data is sold to certain parties for bad purposes, where we as data owners do not know anything.