Slots gambling is totally based on luck
Actually slots are the only one that run on math.
Unlike a roulette that can one day never trigger a winner or the next day have a winner on every spin, slots machines always calculate how much money they will eventually give out, usually 95-98% of what they had on deposit.
In the past if you would know how much has been already played there and how much the machine has to pay in the future you could abuse the system, this is what two employees in a casino have done, pretending to reset the data of the slots machines after taking out the money but not doing so and informing their partners if a machine had already a positive balance of over x100%, so it has paid less than $10 instead of $90. When finding one their partner would simply sit at that machine and spin till it will get a positive balance, due to the different in the already cashed in sum the 5% the machine usually takes was no longer to fear.
Of course newer machine are no longer subject of this exploit, first they don't show that data anymore by just fiddling with the key and second they lower the payments if someone plays continuously a game on it, exactly to prevent this waiting game on someone else's money!
But slots gambling is the only one that truly is math.
If you would sit all day for he rest of your life at that machine and bet 100 millions dollars till the machine rusts I can tell your for sure you're going to lose 5% of it or how much that machine takes, one penny more or one penny less. For sure you won't make a dime but also you won't be losing half of it either!