I'm in my 40s, lots of people I know got on Facebook a long time ago and never had any interest in jumping over to whatever the new social network is. Some of these people are people I knew in high school, or college, or people who moved far away, or people who just settled down with kids and don't really get out much more. People who I still am interested in having some contact with, but I don't really directly interact with much directly anymore. Facebook is the perfect level of contact with these people. I certainly use Facebook far less than I used to but I still log in once in a while for a reason.