I read of a chap who was poisoned by eating a cupful of apple seeds for a bet. So don't try that. But a cupful would be hundreds of apples-worth.
I always eat apples from one side through to the other, including the core. I've not died yet. I've known several people who eat them in round slices, top down, including the core. The pips are a little bitter if you chew them too much, but otherwise the core's the same as the rest of the apple, and you don't have to find somewhere to put it.
What Rabelais says about cyanide is correct -- if there's not enough to kill you straight away, you're pretty safe.
Cherry-laurel leaves have loads of cyanide, but my cattle eat potentially lethal amounts of them(anything over about 1 kg) without harm, because they do it slowly enough and eat other stuff in between.