Car keys
Some already alluded to hackers using other methods of breaking into systems these days.
Just like the security of modern cars is such that it's all but impossible to break into them and drive them off, so would-be car thieves simply change their mode of operation to steal the keys. There are all sorts of tricks they pull to trick motorists into stopping, or they just break into your house and steal the keys.
A chain is as strong as its weakest link. So much of what passes for security is focussing on one link, which is far from the weakest already, and trying to make it ever-stronger. In the meantime the weak point is elsewhere.