Are you still keep in contact with your childhood friends?

I had a load of friends back to childhood. no one moves out of the city until now. but you know people change, and we seldom talk to each other again when we went to high school. just a few weeks ago, I sent a friend request to my childhood best firend(not now apparently) on facebook, he even rejected it... any way we don`t have much to talk anyway. now I have two bestfirends, but will they be gone just a couple years later?? why everybody around me is come and go???