Mafia? In my experience lots of singaround singers know each other and are old friends. How does that make them a Mafia?

Everyone of those people sang for the first time in front of other people, and we (mostly) remember that. And, in my experience, they are very welcoming of new talent. All the singaround organisers I know are very fair about giving each person a chance to sing, but in a large singaround it can take 2 hours or more to get round. Perhaps you are not waiting long enough.