What made me marvel at it was how incredibly effective that strategy is, and simultaneously how easy it seems. Think about a stereotypical pyramid scheme. In it, you start off by selling products on your own, but are encouraged to get six people to sell things on your behalf. In my experience, getting six friends to do anything consistently is impossible. One would be into it, two might stick around for a couple months, two would give up after a week, and one would never show up. But what is important here is that one was really into it. So now I as one person have reached one person.
The other part of this is the power of exponential growth. Even with having each member of your group reach one new person, you are doubling your membership each time. After not many iterations, this process reaches incredible amounts of people. If you started off as just yourself, then after 10 iterations, you would have over a thousand members. And after another 10 iterations, you would have over a million.
Your ability to reach people is phenomenal, especially when the people you reach then reach out to more people.