The fact is that quiting gambling is very difficult as we have more people suffering from losses and addiction. Also those who're winning won't want to quit as well because they're benefiting from gambling and fir then to quit means they should give up their source of income.
When we get used to doing something on a regular daily basis, there's no doubt that we are more likely of getting addicted to it and this apllies to many people across each settings of life, gambling is not what we do because we feels it's a necessity, we desired to gamble because we have passion for it which makes it uneasy task to accomplished whenever we decided of quitting from gambling, but as you have said, some may not want to quit because they earn from it and also get entertained while those interested in quitting may not afford to get away with the losses they've incurred at the process.
When we gamble regularly, even a little bit of it can become addictive. Quitting gambling is not an easy task even if you don't lose money due to addiction in gambling. Because here some can take pleasure through gambling. Some people think that if he loses gambling he will quit gambling but is it really possible? From my point of view no one can quit or hold a gamble because of winning or losing. Quitting gambling is definitely a difficult task for a gambler. So I think it's easy to join in gambling but very hard to leave.