It’s actually possible to win real money, admittedly smallish amounts but money nonetheless, from free slot machines and there are a surprising (and growing) number of online casinos that offer free slot machines.
Just do a Google search for ‘free slot machines’ and you will come up with hundreds of thousands of hits. Why would they do this you ask? Well it’s just another way to entice players and encourage them to register to play with real money. The prizes on offer by these online casinos if you win are typically credits which are exchangeable for real money to play with at the same casino. Or your prize might be the chance to enter into a draw. And even if you don’t win anything, playing the slots for free without risking any money is still entertaining.