You are not Facebook's customer; you are their product

Facebook has frequently been at the centre of privacy concerns and this is no surprise, since their business model consists of getting as much information from you as possible and selling it to their real customers: marketing companies. It is in their interests to keep making more and more of your details public (as long as you are no so annoyed that you leave). However, even then, notice how difficult it is to delete information from your profile (and Facebook most likely retains that information even once you've taken it down) and that it is very difficult (though not impossible) to delete your profile; if you try, you are encouraged to simply "deactivate" it until the point in time you wish to take it back up.

You are not Facebook's customer, you are their product. Keep that in mind.