I'm going to get slated for saying it poor training. People will say that no matter how much you train it, it's a wild animal.
But there are thousands of trained chimps that haven't ripped someone's face off. With good training, including good handling, chimp ownership is safer than say... cooking.
The difficult part is making sure the owner is competent. To own a potentially dangerous animal (including larger or more aggressive breeds of dog), you should have a licence. A licence which you can't just pay for.