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.
What is the casino that asks for a 100x wagering requirement for a bonus? That is just like simply not giving a chance to the gamblers to take anything home with the bonus since the amount is sure to be lost while trying to complete the wagering requirement and there will be nothing left for withdrawal by the time the requirement is fulfilled.
Such casinos are better left alone, people should choose casinos and platforms that have good bonuses with reasonable requirements where if you get a bit lucky, you can at least get something out of the bonus provided.