Laundering through casinos isn't easy. They track the amount of cash you put in and out. You can do small numbers but you can't bring in 100k then spend 1000 then leave.
I used to work in a casino and most of our business was drug dealers or small business owners laundering money. There were a few dozen gambling addicts and occasionally a young sports star with an escort on his arm and more money than sense.
It is simple. For European Roulette you place a red bet for x amount on one machine for the 1st wheel. Then the same x amount on a second machine for the same 1st wheel. Place ×/36 on zero to cover your loss. If zero comes in you break even, if red or black come in you lose the x/36 bet.
Or you could learn basic strategy for Blackjack, with has a mean casino edge of 0.5% over the long term. So by betting $500 every friday night for a year, you'd clear $26k, keeping $24.4k.
Then there is cash pocker, you sit down, pay the blinds for an hour, make an all un for the first pair you get. Buy in a again for a larger amount "to win your money back", sit for another hour paying the blinds, then cash out because "the cards are shit tonight"
On dice there is a 5/6ths chance you won't roll a 7, so you cover all the bets but 7. You win some and lose some, then cash out.
You could easily clear $100k a year, without it looking like you aren't just using recycled betting money. From one casino, from one person. The government is well aware of this too, they just like that sweet tax revenue from the black market too much.