With each passing day, I look less and less like a lunatic for avoiding facebook (and its ilk) like the plague. You should try it.
My friends never send SMS any more, they use Facebook messenger. Nobody asks you for your phone number, they ask to add you on Facebook. Nobody invites anyone to anything without creating a Facebook event.
If I suddenly leave Facebook I am certain I'll also lose out on a lot of social life.
What do you use for instant messages? Do you just use email a lot more?
I really wish some kind of distributed social network could take off the way Facebook has. I do not want anyone to keep my data as much as the next guy, but if you want to be a social person in 2013 (at least here), you kind of need to have a Facebook account.
A guy I met at the start of the semester is a german exchange student. He had to create a Facebook account when he got here because pretty much everything happens on Facebook. Some things do not even have their own website, just a Facebook page.