The version that sort of works are "existence futures" (that's not the standard name, unless I happened to reinvent it). Eli pays someone $1 now, and that person pays Eli $N dollars in M years. N is a combination of the interest rate and the person's belief that they and Eli will still exist in M years. If I think there's a 50% chance that the world will end at the start of 2016, and Eli thinks the chance is 0%, both of us would see a deal where he gives me a dollar now and I give him $1.50 on Feb 1st as profitable.
The trouble with them is that if I really think the world is likely to end on Jan 1st, I'm probably making a host of similar decisions that make it unlikely that I'll actually be able to repay him on Feb--if I'm selling everything and playing video games until the world ends, then when the world doesn't end, where is the money going to come from to repay Eli?
where is the money going to come from to repay Eli?
The usual answer is escrow.
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