Some autonomous cars will be hacked in the future. But it does not mean that they are not a great idea. If we reduce car accidents to half of accidents we have now it would be amazing. Imagine being able to drink and then return home safely, on your own car. Imagine being able to pick up your kids without having to go, or playing with them instead driving. Or having sex with your significant other instead of driving, or lurking on the internet instead of driving, etc. Autonomous cars are a huge deal. Some of them being hacked is not a reason to not have them.