The british government paid out more and more money for cobra skins, but the infestation didn't go down at all. The authorities ended up finding out about the cober breeding,. they stopped offering the bounty, because clearly incentives weren't right. And all the cober farmers just let the cobras go into the wild. You end up with more of a problem than you had in the beginning, because incentives were perverse  and the britishgovernment didn't think about second order thinking.