To give you an understanding of how many people 3 hops in a network is I just checked my Linkedin profile. A 100+ connections gives me access to about 3 million people. So I have 100+ connection, my connections each have 100+ on average as well, as do the friends of my connection and this results in a number in the millions. Do I actually know 0.0004% of those people? Hell no, nor will I ever.
Yep, it's kinda funny actually and it can get even worse depending on your interpretation of "connections". For example, let's say a person of interest is a registered GAF user; is every single user of GAF related to said person? are even guest ("identified" by their IPs) related?
Scary times my friend, and even scarier that some people defend these stuff.