I doubt he got one year or any deadlines in his mind. Most of the hackers do this because they know that there's an exploit somewhere.
Come on, how many bugs do you produce, while writing code? Do you bet 500$ that you are bug-free? Do you bet 500$ that the libraries that you are using are bugs-free? I don't.
In this sense I think guys like him are having a way of thinking more similar to a gamer : "I need to do this and I come to the next level, but the experience playing is more important than the next level!"
So... I doubt he thinks there's a 50% chance. He's just too good "gamer" and he knows the games so good that he actually won the four different versions of it.