We can say gambling is wrong if we lost money on gambling, and if we earn money from gambling, I think you guys would never say that, haha, so every statement about gambling is based on the results, sometimes we are down some money but sometimes we are up, just cash out when you are up, that must be correct. 
But most people are never satisfied from what they got, although if you win big amount of money on the next day or may next week you will try it again to win that much, thats why if you can control it not to play it again you wont lose that much. But gambling is too addicted, once you start its hard for you to let go