It seems like the system already has 100% collateral (at GS price). So when 75% more is collected, then it is revived - assuming the same price. So when you bid 75 BTS, you get a net position of 75 BTS: 175 BTS in collateral and -100 BTS worth of MPA. That's exactly what you paid. Net zero (if indirect effects are discarded). So the only way to profit is to participate and wait for the price to rise.