A casino is a place where there is an inflow thousands of people and a lot of cash every day, a threat to criminal activity is highly likely at a place like this. People come into the casino to have a great time gambling and forget the outside world and casinos would want their business to take place smoothly without any criminal activity that ruins the experience for everyone.
In a risky environment like this, the security must be tight in order to protect everyone. With proper surveillance, visitors can have a stress-free time gambling. Fraudsters want to make money by underhanded methods, and they should be caught red-handed (if the chips are red). Back in the days, it was easier for fraudsters to get away, and the casinos would suffer huge losses.
As mentioned before, thousands of people filter in and out of the casino every day, and it is impossible to keep an eye on what everybody is doing manually. With video surveillance, it is possible to detect and stop any suspicious activity. Some people commit fraudulent activities in the games to cheat the casino, and the other players and such people will be nabbed immediately with the help of video surveillance.
Some thieves take advantage of being amongst the crowd and steal the gaming chips of other players and try to encash that as theirs. But with strict surveillance, these thieves can be caught in the act. Some employees involved in crimes can also be stopped too, and they will be fired for stealing from their place of work.