Elek It depends on how many other people invite their friends. Let's say 1000 people invite 1 friend each. Then everyone has individually a 0.1% chance of winning that particular jackpot. If you are one of the people but you invite 5 friends instead, then your chances rise to around 0.498%, which is almost 5 times as much.
How many people are actually inviting other people though, that is unknown. So it's also not possible to know exactly how your chances are affected by inviting more people. If we assume that at least a few dozen people are inviting other people every month, then to get the best odds with a limited amount of friends and family that you're able to invite, sending just a single invite every month would probably be the best course of action. Because going from zero to one makes percentage-wise the biggest difference. But then going from one to two (under the aforementioned assumptions) would only at most double your odds.
