Bonus is just an attraction of the casino to convince many players to gamble on their casino. It sounds good because of the term not knowing the rules associated with it. As you've said the wagering requirement needed to be able to withdraw the bonus is hard to fulfill but its not a pain to try right? But this is if you're playing for fun, otherwise it can get your funds busted. The reason why I prefer the casino's promotion over bonus because there's a chance to get real earnings through it.
Casino platforms that offer high bonuses are only the attraction for casinos to appear superior to rival casinos, but you are right that the bonuses offered cannot be owned because they have to meet difficult rules, so that in the end gamblers get bored because bonuses can only be used for betting and not added for fiat withdrawals. So it's better to use the top casinos for a chance to win from promotions than from the "fake" bonuses on offer.
I know that's the marketing strategy that most casinos do here in cryptocurrency. But from another angle, if we look closely, the bonuses they supposedly give, in fact, also come from the amount of the depositor who gambled.
For example, other casinos say they will give a bonus of 25$ to those who sign-up on their gambling platform, but before you can get the bonus of 25$, you must first deposit an amount of 500$ on their platform. Do you think that the 25$ will come directly from the owner of the gambler, of course, it will not come from the gambler's money. It's a bit tricky to get there.