There is truth to what you say. People who complain about not having any friends and how the whole world is out to get them typically are the ones who bring it upon themselves. But then some people like to be more isolated and some just have difficulty around people. There are thousands of different variables that go into it and, just because someone doesn't have a lot of friends, doesn't make them a "loser" or a bad person.. :/
Speaking from experience, I had a huge circle of friends at one time, but eventually it shrunk to a very small group and there have been times I really haven't had anyone at all, so I've seen it from both perspectives. Some folks do have valid reasons for the way they are and may have difficulty helping it or they just don't want to help it.