To clarify things better here is an example : if you were to deposit $1000 and win $200 in your first few games then you wouldnt be able to withdraw your winnings or even your deposits without wagering at least $5000. This means that 80% of the time, you would lose your money before reaching the required amount.
In my opinion this term is unfair.
This is not fair at all. Yes, I have seen casinos require their players to wager 50x or more if they take deposit, welcome, or other kinds of bonuses. That make sense because they won't give you something for free. You have to play there and you have to win. I also saw casinos need a wager requirement for any deposits to prevent money laundering. But, it was no more than 1x. Having five times wagering requirements on each deposit is not fair at all.
You should avoid that kind of casino at any cost. Of course, you have to read their ToS before you sign up and make a deposit. Because they may already mention this term on their ToS page. If you can make your first withdrawal from their platform, run away with your money and never look back. Those casinos are designed to steal money from users.