They would become non-naive by being harmed (by losing a pile of money). Of course that's a lesser harm than being killed, and indeed "kill the non-resistant ones" is different from "harm the non-resistant ones until they become resistant", so I probably shouldn't have included the diseases-in-the-water example because it uses both effects. It's the latter that I had in mind as common to the examples I listed (as well as, of course, Clarity's original proposal).