If you won in gamble and earn a profit ofcourse that this is so much fun. That's why many people keep use to it. While you are having fun still you can earn your profit
There's no other thing that is fun in this world and that is by earning and it can be apply with gambling. I used to have fun before but I have understand that there's no need for me to have fun and waste money at the same time. Though sometimes I fail when I gamble because I keep on losing but there are times that I can't stop winning. It's either fun and win or fun and lose.
People may gamble to have fun, but when losing consecutively then it is not fun at all. No matter if they use free money or not, if lost continuously it is not fun. Profit and fun can be occasionally we get from gambling, sometimes not.
There's no one that is having fun when he's losing for many times consecutively. But as you say with free money that is something new and it's fun if you'll just gamble with free money as you lose nothing when you lose and when you win, you gain out of nothing that's an easy profit for anyone that will gamble coming from thin air. Profit will be the main reason all the time why majority is gambling.