You know sometimes, achievements like that can hit us really hard that we begin to count losses instead of our gains.
Probably the guys saw the amount of bitcoin he has wagered away and right now, he doesn't have even have up to 10 bitcoins in his account/wallet, so he realized that he's lost far more than he gained.

This kind of thing have happened to me before, when at the end of the year, I requested for a statement of account from one of the banks I used, from the document, I realized that over 15 million Nigerian naira has passed through that account in one year, and I don't even have up to 500 thousand Nigerian naira on that same account or any of my accounts, so I began to seriously ask myself what I did with all that money, it broke me down for several weeks.

So maybe the guy is going through same experience right now which is why he asked that his account be closed.
This is just me speculating based on my own past experience, I might be wrong though..