The final conclusion is incorrect. I've gone into detail responding to heeton, but I now thought of a simpler way to explain it. First, the case in which you a

The final conclusion is incorrect. I've gone into detail responding to heeton, but I now thought of a simpler way to explain it. First, the case in which you are the only entrant is irrelevant. Your chances are already 100%... why share? For all other cases, think about this: -Getting one extra entry DOUBLES your chances of winning. -Supposedly, the network effect of inviting friends offsets the above. Think about what that means. The number of people you are able to get to join through invites has to be MORE THAN HALF of the total number of final entrants (if there are 10,000 entrants already, you have to cause at least 10,000 more to join to offset the doubling above). The author is essentially stating that by the end of the contest the majority of the entrants will have been caused by you. There is no universe in which this makes sense.