Gamble is played with the aim of earning more money. Therefore, not earning money often leads people to try to cover up their losses by betting more and more. Gambling addiction is the fault of gambling, even though I still think it's acceptable for people to do it.
It is not really that case all of the time. Sometimes people are just playing for fun therefore they dont really lose that many compared to people that play for profit. Im quite sure that the number of people that play for fun is relatively low compare to those that play for profit however Im sure that there will be many more in the future when they realize that it is for entertainment
Playing for fun is subconsciously playing for profit though. It's basically just playing for the adrenaline, which is from the possibility of winning more money as well as the uncertainty of whether you'll win or lose. It's more than just fun, it's what the the cause of you having fun actually is.