The number 7 is seen as lucky in slots and pop culture because it often signals...

https://rowansnewthoughts.quantlynix.com/posts/what-do-bells-mean-on-classic-slot-machines

The number 7 is seen as lucky in slots and pop culture because it often signals big wins, like hitting 777 on classic slot machines. Its luck ties back to the seven-day week, symbolizing completeness