Odds from here:
I might be completely wrong but looks like your estimate yield is heavily dependent of amount of other people saving as well.
I bet the real model gets pretty damn interesting. Would love to get a closer look for sure.
If you wanted to be a bit more "evil genius". It would be interesting if somehow the money in the grandprize grew based on how many people participated. This would give people incentive to join and lower the overall EV for everyone, but also give you guys more funds to manage :)
- Odds for the $0.20, $0.80 prizes are slightly off.
- The $15 and below prizes are not split between participants, so one would not need to consider the number of other entries for winning those prizes.
If one just considers the $15 and below prizes, I think the odds work out to about 3.2% per year, making it about a 3.4% expected interest total.