Ha....
In many cases, you are right. I have learned to avoid those people as much as possible. The theory that I have is that since us car guys are a minority of the population, many of us are happy to be able to mingle with other car guys when we can. Some car guys seem to be socially awkward and just do not interact with others often enough to develop social skills.
Also, I don't know if the majority of us are aware of how self centered we appear to others. I don't think that people intend to monopolize the conversation. It just happens.
It can be corrected though. Self awareness is a great thing.
Me? I ask a lot of questions when I meet new people. It is a great conversation starter. It isn't always an effort to bridge to my own interests either. I like to learn of how others built their cars. If I am talking with someone and they show absolutely zero interest in anything other than themselves, I move on.