If FB's job was once again just to show me my fucking posts, instead of building the most complete profile of a human being in the history of mankind so that it can sell me out to governments and corporations, it seems to me the data load would be a lot lighter.
Of course they do also collect a lot of behavioral data, but I imagine all the data Facebook has collected on me probably uses up less storage than my profile pictures alone...
Hmm, but that's how they make money. They log, they analyze, they show you ads and they sell your data.
Edit: So downvoters, how do I buy data about Facebook users?
In the meantime, find yourself a dodgy intelligence agent or sysadmin.
It's too bad Facebook and Twitter are businesses, instead of multiple protocols and multiple businesses. Or in other words, it's too bad The Old Ones didn't think cat pictures and what they had for breakfast was important. https://en.wikipedia.org/wiki/List_of_Internet_pioneers
EDIT: Changed to intended link.
As per [1], in March 2014 they were handling 20B messages/day (with 600M pics, 100M videos) with just about 550 servers.
My guess would be that, every day more photos are shared on WhatsApp than on FB.
Major difference: At present, WhatsApp does not "keep" your messages or sell "you" to advertisers.
[1] http://highscalability.com/blog/2014/3/31/how-whatsapp-grew-...
[1] http://www.datacenterknowledge.com/the-facebook-data-center-...