All activity on social networking sites is deceivingly permanent. Every 'like'; every comment; every interaction is noted and recorded somewhere (the cloud.) It may only be a matter of minutes before a top story falls from everyone's news feed but the data still remains. A ghost of the comment, or expression lurks behind, to be collected and harvested just like any other source of data.
Our blogs and posts will outlast us. Putting aside a possible huge server fail or Facebook being shut down entirely our day to day narration of our social lives will live on long after the friendships or even people continue to exist. This is appeals to a desire many of us have, to go down in history, to create or to do something that will be permanently recorded. For the non-religious this idea soothes fears that death really is the end, that although we wont be able to sense or enjoy it, we still may 'live on' in some way as a citation.
However, it's not like our best moments are being recorded permanently. At best what will be 'attributed' to me (not that anyone will 'read' this data, it will be processed automatically) will be a collection of interactions I made (Liking stuff, attending events) at worst it will 'read' like a diary. I used to keep a diary, that's not how I want to live on after death.
After coming to this conclusion my online habits changed a lot. Even if what I post on the internet wont necessarily be attributed back to me, the fact that it will last as a record of what a human did with his leisure time makes me think twice before posting