The number 7 is seen as lucky in slots and pop culture because it's often...
https://mike-wiki.win/index.php/Why_Does_Seven_Show_Up_in_Calendars,_Religion,_and_Games_at_the_Same_Time%3F
The number 7 is seen as lucky in slots and pop culture because it's often linked to good fortune, like the classic 777 jackpot on slot machines