Exactly this is your mistake my dear. But this condition is not good. And there are many casinos which impose these kind of terms to the users. And some of them change the terms and conditions but they don't inform the users this is not good too. These casinos should bold these kinds of terms on the terms and conditions page which will be clearly visible to the users and users will be aware.
The biggest mistake anyone will make is in not reading the terms and conditions of the casino to properly understand them better and as a matter of fact it is impossible to adjust to them when you already reached the point of withdrawal and being faced with a slamming high wagering requirement to make your withdrawal possible and this has become the major problems facing most gamblers because they failed to read this wagering requirement always leads to some unfavourable ending where their almost lose everything trying to withdraw their winning at some point.
But regardless whether or not the player read the terms and conditions of the casino, slamming a player with a 5x wager requirement to withdraw is something that should be considered unfair to the gambler.