Summary

The event takes place in a hired hall, in which the fees are taken from prediction fees. With no rules that say everyone must bet, Ivan could suffer loss from the lack of prediction fees.

Vulnerability Details

Assuming that all 15 of Ivan's friends understand that the hall is paid through prediction fees, they are likely to put the bets. However, since there are no rules to enforce this, the remaining 14 players may not bet and therefore there is a hall fee shortfall in which it should be covered by Ivan.
We can determine the upper limit of this fees by multiplying the predictionFee with the total number of games and players, but there is no lower limit on this.

Impact

Ivan may suffer loss from the fee shortfall.

Tools Used

Manual review.

Recommendations

Make sure the hall fee is covered. Since only registration fee is guaranteed, Ivan should take this to pay the hall fee.