In colonial India, Delhi suffered a proliferation of cobras, which was a problem very clearly in need of a solution given the sorts of things that cobras bring, like death. To cut the number of cobras slithering through the city, the local government placed a bounty on them. This seemed like a perfectly reasonable solution. The bounty was generous enough that many people took up cobra hunting, which led exactly to the desired outcome: The cobra population decreased. And that’s where things get interesting.
As the cobra population fell and it became harder to find cobras in the wild, people became rather entrepreneurial. They started raising cobras in their homes, which they would then kill to collect the bounty as before. This led to a new problem: Local authorities realized that there were very few cobras evident in the city, but they nonetheless were still paying the bounty to the same degree as before.
City officials did a reasonable thing: They canceled the bounty. In response, the people raising cobras in their homes also did a reasonable thing: They released all of their now-valueless cobras back into the streets. Who wants a house full of cobras?
In the end, Delhi had a bigger cobra problem after the bounty ended than it had before it began. The unintended consequence of the cobra eradication plan was an increase in the number of cobras in the streets. This case has become the exemplar of when an attempt to solve a problem ends up exacerbating the very problem that rule-makers intended to fix.
The Cobra Effect: Lessons in Unintended Consequences (fee.org)
Interesting. As an aside, I am a father of four.