Stop living in a vacuum. One billion people have a Facebook account. It's possible that your close friends are not in that group, but the average person on Earth does, in fact, use Facebook.
The population of the earth exceeds 7B (http://www.census.gov/population/popclockworld.html) so in fact the average person on Earth does not use facebook
*unless you live in a vacuum where 1/7 counts as half
"Stop living in a vacuum ... the average person on Earth does, in fact, use Facebook."
No qualifications made for internet access
You can't just take your single data point (my close friends aren't on Facebook) and then extrapolate it (most people aren't on Facebook).