Comment by nine_k
Lotteries, too: https://www.acamstoday.org/lottery-and-money-laundering-a-ma...
I remember reading about a case where criminals bought an entire issue of a local lottery, thus collecting all the prizes, and apparently saw that a reasonable cost to launder their cash.
this works quite well even at small scale. In my country you can just go to any tobacconist, buy 1000 € worth of scratch cards with cash, and happily keep whatever comes out. And since they're heavily regulated, you can check winning probabilities in advance so you already know the expected return!