Or at least the loss rate should be the same as the fail rate. If I have a 50 % of failure then if I fail I should have a 50% of retaining the star. When you get to 8 stars and have a 10% chance of gaining and a 90% chance of losing there is no real incentive to spend the gems to take the bigger risk of loss. Even Vegas doesn't rip you off with those kind of odds.