Yes I'm aware of that definition, and I still think it is a legitimate example of tragedy of the commons. The commons here is an abstract one: it's the lack of

Yes I'm aware of that definition, and I still think it is a legitimate example of tragedy of the commons. The commons here is an abstract one: it's the lack of incentive within a society to perform a kidnapping, which is a shared benefit/resource. The family of the victim who decides to pay the ransom is taking from this commons (by decreasing the lack of incentive), making everyone worse off in expectation, in order to benefit only themselves and the specific victim they're trying to help.