I think you're underestimating the scale of this problem.
According to http://www.datacenterknowledge.com/archives/2013/01/18/faceb... , people upload 350 million new photos per day, and they have 240 billion photos total. If we use 1 MB per photo as an average, you'd need about 334 terabytes to store a day of Facebook's pictures. You'd need 228882 terabytes to store the whole thing. Assuming Wikipedia's estimate of $35/TB for desktop hard drives, it would cost about $8 million to store Facebook's photo archive (that's without videos or text). Actually hosting it would cost even more.