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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.