Looking up "bonus money casino" usually happens after a bonus has vanished, taking its winnings with it. The cause is almost always a condition in the terms: a deadline that passed, a withdrawal made too early, a cap on winnings or a clause about irregular play. Each of these can be seen in advance, and a short read of the terms shows which of them apply to a given offer.
Requesting a withdrawal while a bonus is active often cancels the bonus and everything won with it, and some casinos apply the rule even to cash deposited alongside it. A player can usually cancel a bonus on purpose from the account page, which frees the cash balance at the cost of the bonus. Knowing where that option sits, and what it removes, turns an accidental forfeit into a choice made with open eyes.
Bonus terms include clauses on irregular play, and they are written broadly. Typical examples are betting on both sides of an even money bet, switching to low risk play to clear wagering, raising stakes sharply after a bonus is converted, or opening more than one account per person or household. A casino that finds such a pattern can void the bonus and its winnings. Reading the clause shows which patterns a casino names, and which ones it leaves to judgement.
Casinos can revise their terms, though most promise that a bonus already claimed stays under the version the player accepted at that time.
A saved copy proves which version of the terms applied on the day the offer was taken, which matters if the casino later changes them.
Often yes. Asking to withdraw while a bonus is active can remove the bonus and its winnings, and some casinos apply this to the deposited cash too.
Usually not. Opening more than one account per person or household is a common abuse clause, and it can void the bonus and its winnings.
A saved copy of anything support agreed settles disputes far better than memory, especially if the promise is later questioned.
A limit on how much can be withdrawn from bonus winnings, often a multiple of the bonus or a fixed amount; anything above it is taken back at conversion.