My experience of going to high-end casinos, mostly in London, is that: - Many players were plainly cheating in some way, by marking cards and sometimes colludi

My experience of going to high-end casinos, mostly in London, is that: - Many players were plainly cheating in some way, by marking cards and sometimes colluding with the dealer, but the casino didn't appear to mind because they were cheating in an ineffective way and still losing money to the house edge. - (Related: you would just be banned if you won an amount of money that showed you were beating the house edge: see also the Phil Ivey lawsuit) - Some players were gambling large sums of money generally on games with a small house edge, and looked bored like they were there to do a job. I assume from their behaviour they were laundering money.