Playing with fake money has a way of even giving a player more chance of winning and luck than when you use real money which always gives a false impression that you are ready but non-ideally, you are just preparing to feed your money to a casino because you will lose to them.
It is not as if gamblers don't just want to play with fake money, they do but there is no joy in winning fake money you wouldn't be able to withdraw but there may be fun in trying and getting the experience of the game especially if you don't know much about it.
By experience, you probably mean the ability to play/knowledge of the rules and game mechanics (poker or blackjack or something similar)? Because I don't know what kind of experience comes from playing slots where the player presses one button and watches the result. Even in dice, you can say that it is interesting to try different auto-betting settings (different strategies), but it is clear in advance that in the end you will still lose. And by the way, playing for fake money, for example, poker, will not give all the experience that a real game gives, since in a real game a huge component of the strategy is psychological pressure on opponents by raising the bet.
In real games pressure and aggressiveness are mostly influences your decision making, unlike with fake money where you can go all in without worrying but if you are using real money the chance that you will fear in losing everything will reflect on how you will play with your bankroll, so with aggressions when you already feel the adrenaline it can push you to make un-plan decisions.
Fake money will just let you enjoy the game and nothing more, but real money will give you the entertainment and excitement
that might lead you to lose a lot.