Festivals have long included games of chance, from dice at Saturnalia to teen...

https://andressinspiringthoughtss.theglensecret.com/why-was-gambling-allowed-during-saturnalia-but-banned-the-rest-of-the-year

Festivals have long included games of chance, from dice at Saturnalia to teen patti during Diwali and mahjong at Lunar New Year. Setting a clear end date using calendars helped keep gambling part of the celebration, not a year-round problem