I don't really know how to get around the problem of people placing bets with money they possess probabilistically. Clearly, if enough people are doing it, and

I don't really know how to get around the problem of people placing bets with money they possess probabilistically. Clearly, if enough people are doing it, and enough of them make the same bad, massive bet, we all get screwed. But at the same, everyone in finance — even the most vanilla, small-town, we-just-take-deposits-and-make-safe-loans banks — works with money that has some nonzero chance of shrinking. The difference is that some correctly account for their worst-case scenario and others don't. Not sure where I'm going with that except to wonder whether there's some system that allows for speculation (i.e. opportunities to make money by making the right bet where someone else made the wrong one) while not tolerating a nonzero chance of a 2008-style meltdown.