There are many metaphoric phrases to indicate randomness, several of which relate to gaming
toss of a coin
flip of a coin
throw of a dart
spin of the wheel
luck of the draw
cut of the cards
your guess is as good as mine
Some expressing lack of control suggest futility
chaff in (on) the wind
a drop in the ocean
like looking for a needle in a haystack
snowball's chance in hell
a face in the crowd
Phrases suggesting a causation, rather than lack thereof, tend toward other images often based on scientific or mechanistic processes or human industry
laser-like precision
as sure as night follows day
in lock-step
you reap what you sow
you get what you pay for
what goes around comes around
you can bank on it
like clockwork
"If you build it, he will come" (reference to the movie Field of Dreams based on the novel Shoeless Joe)
A few dependability references do use gambling metaphors
bet your bottom dollar
a sure thing
ace in the hole (implying you have a hidden advantage)
a safe bet
Some are based on questions, occasionally scatalogical
Is the Pope Catholic?
Does a bear shit in the woods?
Does a tiger have stripes?
Will the sun rise tomorrow?