The casino operators need to think about the law of large numbers. If you have an edge, what you want is for a bunch of little guys to bet against you. Your certainty of winning against a million little bets is enormous, if you have an edge. And you do, because those games are made that way. What you don't want to do is bet a few big bets. You might be smarter than me at guessing the outcome of an election, or a coin…
The casinos more than understand this. They can tell you the break down between whales and average gamblers. The problem is there's a really uneven distribution. They probably get 50% of the wagers from 1% of the gamblers. But they still have enough whales that they rarely have a losing day.
If indeed a whale was betting 100 million on black or red at roulette, and the total bankroll of the casino was 500 million.. it would be very easy for the casino to go under.
But if the max bet on a spin of roulette is 1 million dollars, and the casino has 1 billion dollar bankroll.. you can do the math of the odds of a whale busting the casino. Hint: It does not look good