The number 7 is seen as lucky in slots and pop culture because it often appears...

https://kylersexpertthoughts.almoheet-travel.com/why-do-slot-reels-usually-need-three-matching-symbols

The number 7 is seen as lucky in slots and pop culture because it often appears in winning combinations like 777 on classic reels. Its charm also ties to the seven-day week, which feels complete and balanced