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

https://spencersnewinsights.capitaljays.com/posts/why-do-flaming-sevens-show-up-in-modern-slots

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