The games are only meant to help you get to know them and have fun with them right away. You definitely have fun when you see winnings - at least I do 
This is how casinos tempt you basically. This is common knowledge to be honest. Demo mode usually help you win a lot more often in both FIAT and crypto casinos. I usually avoid demo mode in crypto casinos and focus on playing with real money since it's possible to bet miniscule amounts in most games thanks to low minimum bets. Great mix of fun and low risk gambling.