But I also don't believe that either system is likely to be a money- (Bitcoin-) seeking scam, either.  The reason is based on Game theory.  Imagine somebody starts up an AP-type operation.  Imagine further that it is acting is what I'd call a 'healthy' fashion, actively collecting at least dozens of hundreds of individual donations per day.   (This would be strongly impeded if the system collected minimum  donations of 1.0 BTC, like Sanjuro's system started out doing , or it was somehow not sufficiently easy to use, or it did not provide the various proofs of operational security sufficient to induce confidence in potential donors.)  I think if it was 'working', such a system would quickly develop hundreds of target-names, albeit some with tiny reward amounts,  and would certainly collect enough donations within, say, three months to raise the bounties to a level sufficient to result in at least one, uh, 'hit'.  Prior to that, many potential donors would still hold back, either because they weren't confident that somebody would be rewarded, or they would wait to see if something 'happened'.

     But suppose that one 'hit' occurred.  Suppose the system demonstrated that some unknown-named person had correctly predicted the date of death of the person listed. (This should be unavoidable:  It should not be possible for the system to conceal the existence of a correct donation; in any case, the public and all potential future donors would insist on the exposure of all relevant donations naming that particular target.) Would the operator 'defect' or 'cooperate' (both are terms used in Game Theory.)  Would the operator of that system actually pay the stated  amount, or would he refuse?  (I am assuming that the system was at least set up to have the technical ability to prove, to the public, that the reward had been paid to the correct predictor.)

    To me, it is obvious that if the operator indeed pays the reward, and this fact can be proven to the public without revealing the true name of the correct predictor, for every Bitcoin paid out as a reward, this confidence-building measure will result in at least tens, and probably many hundreds of Bitcoins of further donations from other themselves naming other targets.  In other words, at that point it would become totally illogical for the system operator  to 'defect', to refuse to pay a (relatively) small donation, because by doing that he would be foregoing further donations that would be collectively hundreds of times larger.  (Nobody would donate to a system which provably refused to pay on a correction 'prediction', or failed to sufficiently disprove the non-payment of the reward.) 

      This same analysis would apply after the second 'hit', and the third, and the fourth, etc.  At no point, I think, would the 'assassination market' system operator find it financially more advantageous to refuse to pay the reward, than to pay it and remain in operation and collect far more donations.  He will always be better off by paying the reward.