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

https://post-wiki.win/index.php/Why_is_the_Number_7_Lucky_in_Slot_Machines%3F

The number 7 is seen as lucky in slots and pop culture because it’s tied to tradition and good fortune. Classic slot machines often feature the triple 7 (777) symbol as a top winning combo