<...>
Yes you are right that mate and that's the reason why every casino have their rules and regulations or let say terms and condition cause if they give you a bonus then some casino have a task before you can claim it. But some of them that they required specific amount to deposit in order to have or to get that bonuses. So after signing up to or before creating an account then we must research a little bit what is that casino all about if they are trusted or not.
Yes, because there are many cases that often appear on this forum where gamblers often complain about this, most of them easily get stuck with bonuses without reading the terms and regulations, that's why looking for a good and reputable casino is important because by playing in big casinos there are usually notifications or sort of to remind gamblers to read the terms and conditions to get approved.
In other casinos, it's usually a trap, they don't put terms and conditions that sometimes people are lazy to read, but this is where the importance of gambling is not to be too passionate about doing things in a hurry, for example making a deposit without having to do casino research.
Did you know that there was a time when gambling sites and poker sites weren't really that harsh with the requirements in their welcome bonuses? That's when something called bonus whoring came in when lots of people would go from site to site to collect bonuses and get enough money to build a nice starting bankroll.
It costed many sites a lot of money tho as the whole thing started to get cheated and gamed with multi accounting... Hence the state of casino bonuses today.