The thing that many people forget to think about when analyzing these wins is past loss and win history which is critical. The total profit or loss matters more obviously. Many people simply assume that these winnings only matter.
40 BTC is a big amount indeed, but he could have lost 50 BTC in the past and his overall loss could be 10 BTC.
This means if you stop and take the money out and continue your life like gambling is not even a thing and ignore it completely you will always be in profit however if you keep gambling there is house edge and no matter how big you won eventually it will catch up and you will lose all the money you won plus the money you deposited on top of that.