From a fundamental path, it’s all about building a tree – getting one person to refer many friends, of which a small percentage will go on to refer the next generation of friends, and so on.
Here’s an example of one of the oldest chain letters.
It promised something pretty simple – if you send this to a bunch of your friends, and include some money to the folks on the list, while simultaneously adding yourself to the beneficiaries list, then you’ll get rich.
The call to action is even super specific: Within 3 days, make 5 copies, and send to 5 of your friends. Doesn’t that remind you a little bit of Facebook’s “7 friends in 10 days” internal guidance, in fact? 🙂
The point here is that they had to answer all the questions. You invite people to make money. The channel is email. You invite friends you want to be prosperous.