Basically, slot machines earn on average from $200 toR$300 per day, depending on how popular is that slot machine and what is the house edge. Since players don't have any way to impact the outcome of the game, slots make a guaranteed profit for the casino in the long term.
Each game you play at a casino has a statistical probability against you winning. Slot machine odds are some of the worst, ranging from a one-in-5,000 to one-in-about-34-million chance of winning the top prize when using the maximum coin play.