Let's be honest. He's young, he might not have seen that much amount of Bitcoins in his life. Scamming the members would be an easy task, simulate a hack, and withdraw properly. You're done.
I'm not sure this happened this time (just wasn't following the full story), but something like this did happen with Mt.Gox, right? Also I heard similar stories about some darknet markets. Too bad some people still don't know that stealing is wrong.
Well, bitcoin is money, and with money, there's crime. And stealing is a crime so it's not something to be surprised of anymore. It is just feels a bit scary that this is kind of considered a fact now.