Any casino is created primarily to earn money for yourself. While some players earn money, others lose their money and in order for some players to earn a lot, others have to lose a lot.
It's partially correct, because you're like telling us if the casino can control the outcome which make the winner can earn more than the losers, it's not 100% will be like that because there's still a professional gambler can beat it. This is also the reason not all casino is survive, some closed due to the gambler win a lot, some closed due to internal scam, some closed due to hack, and some closed due to lack of gamblers.