Actually people think and hope their bets will win and make huge money, but in fact gambling is losing money in the long term, because house has edges, bookie has margins, and deposit bonus kills, eventually we are always losing money.
But sadly winning in gamling is not that easy---losing is. Doing gambling as a living because we think that it could be profitable in the long run is not a good idea, it is a suicide for me, taking the risk just because of the desire that we could double our money on it? I don't think so. I'd rather save my bitcoin and make a profit on it in the long run.