Can I drop a pacemaker 0day at DefCon that is capable of killing people?
The problem is that manufacturers are 20 years behind in terms of computer "security". They don't just have vulnerabilities, they have obvious vulnerabilities. That means not only can these devices be hacked, they can be easily be hacked by teenagers. Vendors do something like put a secret backdoor password in a device believing nobody is smart enough to find it -- then a kid finds it in under a minute using a simple program like "strings".