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

https://www.alphabookmarks.win/the-number-7-is-seen-as-lucky-in-slots-and-pop-culture-partly-because-classic

The number 7 is seen as lucky in slots and pop culture because it often represents good fortune and completeness. In classic slot machines, hitting triple 7s (777) usually means a big win