There are some people gamble and lose. if you ask them why do you gamble? They will answer you "just for fun"
They know they are loser in long term and no strategy works, but continue to gamble for fun.
How can enjoy something that you know you will lose? Is losing money really enjoyable? Isn't there any other entertainment you can enjoy?
I think these people are still hopeful of winning back previous losses or they are addicted. Gambling cannot be just for fun. There are many free games too.
It all varies from people to people. Of course literally losing money is not fun. However, there are people who are gambling to socialize and just to let time pass, or to have fun. It's juat that majority of gamblers are playing for money of course.