Markets are absolutely capable of inducing reward hacking in participants. The metric becomes a target. You *think* you're betting on the outcome of an event, but what you're *really* betting on is *what an oracle will say the outcome was*. No matter what the outcome is or how robust it is against outside influence, the *oracle* can be influenced with a gun to the temple.

35/

Which means that the single most important factor in any prediction market is the quality of the oracle. If you let Trump be your oracle, he'll insist (on a daily basis) that his war in Iran is over, and that he had bigger crowds for his inauguration than anyone in history, and that every criminal is Somali, and on and on and on.

18/

The metric - inbound links - became a target - *get* inbound links - and stopped being a useful metric.

There is something quite wonderful and life affirming about the idea of Pagerank: the idea that people are, on average, pretty good at figuring out what's good. Rather than taking Yahoo's approach of having experts rank and categorize every website on earth, Google trusted "the wisdom of crowds" and it worked (until they created an incentive to subvert it).

7/