If it leaks, there is a direct impact on users monetary expenses. One of the examples: FB may know their user's lifestyle - eating habits, drinking habits etc. (based on the content/media users upload) If this info is leaked to insurance companies, it'll have direct impact on the premium you pay.

That definitely turned out to create a terrible misfortune for all of the world and set the evolution of civil rights back about 70 years.

A lot of adultery would come to light </half-sarcasm>