All gambling sites are designed in such a way that your wins are less than loses in long run. For dice rolling sites there is no strategy that will constantly increase your balance, there always exists some small probability that rolls will be made in such a way that they will exhaust all your balance and you couldn't bet anymore. For other gambling games such as minesweeper the probability of win multiplied by your earnings is just less than probability of lose multiplied by your losses.
So guys, never try to gamble or you will lose anything!
