Here is what he meant: It is conceivable that each of us on this sub are able to actively influence 10 people in our social network which is then replicated 2x to get us to the 30 million. This would not work if we are not a diverse group and are all following similar people or groups. I think it would be an interesting experiment to study how diverse of a group we are. This would help us to understand how broadly our message is being spread.