According to a recent article by PetaPixel...
Facebook Rep Claims Uploaded Photos Become the Company's Property
and, in the Terms of use that we all agree upon, it is apparently clearly mentioned that in fact, all uploaded material to the popular social media website, does become public domain, and that anyone can use it.
Ouch!! What about Copyrights laws, shouldn't this law take precedence over a company rule?
Meanwhile, may I suggest to my fellow photogrpahers, to upload as little as possible, make sure your watermark is ALL over your product, and do what I do, and make a link to your Blog and/or Website, where for the time being, laws still protect us.
You can read the article HERE