There are people out there with short-range, wireless pacemakers with no security. Most just provide information you'd expect but some of them are also defibrillators (they can kill). As far as I know none have been harmed in an hacked attack but a hacked brain implant brings to mind more than just killing the owner. We may have an interest as a society in making this illegal because it's not worth the gamble to us for people's actions to be hijacked remotely.