Look into it a bit deeper. That was an elephant that terrorized a village in Africa. It was sanctioned to be put down, no different than a rabid dog.

He is very very rich, if he had particularly cared about protecting the fields rather than shooting elephants perhaps he would have paid for the installation and upkeep of a fence.

His own comment on the affair was "These people have literally nothing and when an elephant is killed it's a big event for them, they are going to be able to eat some protein." Now personally I supect that there are better ways for Bob to go and increase the protein in these people's diets, other than shooting elephants.