actually we must not come to the trap of gambling site that uses bonuses promo but the truth is? they are the one who will only benefits because we need to deposit and play(and surely will lose) and they will gather our money without winning that said bonuses literally.
so best to learn from it and never fall from those traps.
We can use the bonus promo well as long as we don't overdo it in gambling and don't chase victory, which will be difficult to get. Maybe depositing the minimum amount specified to get the bonus will give us a chance to win, but we also have to know that we just play using the bonus and the rest we use for another day. Who knows, we might win more than today and if we still save the remaining balance from being used for gambling on another day, it will give us an advantage where we don't have to deposit any more money.