I started one with the goal of slaying the ended dragon legitimately, but got bored trying to get eyes of ender. So I didn't die after like four days of playing, but I stopped playing that hardcore world.
Hardcore minecraft is just a matter of 'how long will you last until something unlucky happens'?
You won't die to anything dangerous, but eventually, at some point, you are going to die simply because because of some unexpected gimmick or glitch, (pets shoving you off a cliff, shift key got stuck when you needed it to work, etc).
I really don't care for the idea of hardcore since regular minecraft already punishes you pretty severely for deaths as it is. But that's just my opinion.
I am Lord Bowser, King of the Koopas! Bwahaha.. Playing Bowser on Mario Kart, and Noxus on Metroid Prime. I am not a cookie cutter!