I've seen these sorts of conditions for people to be able to withdraw their money. Some are really hard, but you will need to shop around for the good ones. It is almost like we know we will not be able to achieve it with any level of success.
I knew someone once who went to an online casino about 10 years ago, could deposit a small amount and received a random bonus amount, which he had to stake 10* the amount. I laughed when he received a £1K bonus amount and said "no chance". He stayed up the whole night and went up and down in stakes, etc. He achieved the bonus conditions and withdrew about £1200.00. A few of us then thought if he can do it, so can we. Needless to say, none of us got through, but it was good cos he treated us to a night out on his winnings.