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X30-X50 is actually standard wagering requirement for deposit bonus, but if you look at the other thread created by OP, you will find a casino that ask you to wager x10-x30 for deposit without bonuses. I havent checked myself, but it proves that high wagering for normal deposit does exist in the gambling industry and I believe players will not stay long in casino with high wagering requirement for deposit without bonus.
Wagering requirements for Welcome Bonuses can go as high of 100x (maybe even higher). I've seen it before. Personally 30x-50x is already high, however, some casinos tend to set higher wager requirements because there are players that are still able to win through that requirement. Another reason is that they do not want to just give money away (or maybe they don’t really want it at all) so they make it as hard as possible.
The wagering requirements for bonuses I've seen are 100x and I think that seems ridiculous because the requirements are so high and maybe only a few gamblers can get them and who knows how much they have to lose before they can withdraw. Even though there are still players who can win, it will not be within reach of small gamblers like us because we gamble not using a lot of money and just want to have fun so we are not recommended to try to take the bonus. I prefer another reason why casinos don't want to give their money away: they only want to get money from gamblers who have lost. We must prevent it from happening to us and there is no need to try to get the bonus if we see it is very difficult.