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

https://www.beacon-bookmarks.win/the-number-7-is-lucky-in-slots-and-pop-culture-because-it-s-long-been-a-symbol

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