The bigotry doesn’t have to be within a group for people to not want to join. They may be uncomfortable joining due to pressure from their friends and family.

People may also simply not join because they’re not interested. I personally have no interest in going to raves. The music and the drugs have no appeal to me.

Not saying there’s no bigotry in a particular group. Just that bigotry isn’t the only reason why people don’t join.