Generally casinos expect you to bet 1x or 2x before you make a withdrawal, so I agree that it is a bit excessive if they require you to bet 5x before making a withdrawal. Of course we are not referring to a specific casino, but usually this falls within the rules agreed upon beforehand when you create an account. One of the reasons I think is; The casino expects each of its new customers to play longer than the average for other casinos.
And it could be acceptable if the 5x wager requirements for collecting bonus. The requirement is 5x wagers only to enable withdrawal which is not for the bonus. I think it is too much and we have nothing to do except avoid the so-called gambling sites which have too many wager requirements.