The number 7 is seen as lucky in slots and pop culture because it's tied to...

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 because it's tied to classic symbols like the 777 jackpot combination on reels. It also relates to the seven-day week, a familiar cycle