Whether they have trillions of dollar in debt, or they are making trillions of dollars of profit, they are going to charge as much as they think they can get on every single item on your cruise. That is the way any successful business works - trying to determine areas where they can be more profitable and capitalizing on it.
In no scenario will Carnival (or any other cruiseline) say at their executive meetings, "You know what? We have been making a lot of money in the casino, but since we have paid off all of our debt, let's be nice and loosen up the slot machines and make the odds better on our blackjack and roulette tables, so that icft can come out ahead." They wanted your money before Covid, and they want it now. No one is forcing you to gamble.