If you say that gambling is fun is an idiom then I will support your assertion. I have read others have said this in several occasions that gambling is not for fun and when one wants to have fun then they would go to leisure parks to enjoy themselves with games over there. Sometimes with families and friends. The fun is at the leisure parks and not in the gambling casinos Industry. And also I see gambling as means of looking for extra pocket money for the gambler because there is no way some left home and hustle for money and got it then go to the sports book center and play games and loss all then come back home. That doesn't make any sense and it is only insane human can do that.
Gambling is always to find extra money and if you are winning in the process you can have some excitement while playing.