I am just coming acrosss this thread, and i find your question interesting, so i'd give my own two cents.

I don't like the idea of a "group bet", it can cause problems. That being said, if i must do it, it has to be with family or friends that are as close as family, that way i am almost certain that problems wouldn't arise and if problems should ever arise, i'd not blame myself too much, because of the people involved in the whole thing.