Woah, maybe it went pretty rough for the owner. You are really lucky to win 8btc, and seriously i would partly agree with your opinion on what you are saying about depositing.
Well there is really a low chance for you to win because oh very high house edge in this site. In my own experience i was only using the money which do i get from the free spins to play and roll the dice, I win sometimes but most of the times i always lose.
Thats why we should act correctly upon betting so that we cannot be burried by losses after we won even on free spin. And i think he must be lucky for that 8btc winning since not all people got the chance to get that winnings and losses more money on them since as stated they got huge houseedge in their program.