The sad truth is that, only a few people actually plays the demo version of the games if their have the option to play the real game because there is a difference between the two sucne demo games lack some features that are available on the real game because the original game is develop to meet the expectation of bith the casino and the players but demo version is more or less for tutorial and nothing more than that.
I am one of the few who plays demo games. If i feel the need to play slots but i ran out of my weekly budget, i might just play demo versions. That cheats my brain and i for some reason feel more or less the same when playing with real money. At the same time i try to get a handle how much could i get if i was lucky and how much would i lose if unlucky.
I haven't felt the demo versions giving me any more wins then real money which surprises me but i am thankful that they keep the real experience and don't try to lure in with fake high probabilities.