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

https://casinocrowd.com/why-do-people-say-seventh-heaven-unpacking-the-mystery-behind-the-phrase/

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