The number 7 is seen as lucky in slots and pop culture partly because classic...

https://meaninngs.com/what-does-the-number-7-mean-in-casino-games-and-popular-culture/

The number 7 is seen as lucky in slots and pop culture partly because classic reels often feature triple 7s (777) as a big win symbol. It also ties into everyday life, like the seven-day week, making it feel familiar and lucky