Religion is the biggest gamble of all!
You live your life believing your is true and if you have chosen the wrong god you're **** for your entire afterlife!
And just for the sake of discussing the other aspect, no god was around when slot machines were invented, and if any priest/mullah/rabbi whatever claims that everything that happens is the work of their god, then gambling is also a thing the same god allowed happening!
Gambling has existed for a long time even before the founding of some religions.
Some! Since archaic religions predate the use of money or writing, gambling is second to religion on the timeline.