I think if a person keeps gambling away his money and spends a lot of time of gambling, then he is an addict in my eyes. Gambling should be done just for sake of entertaining yourself without wasting too much time or money. It shouldn't get into way of making decision for you and your family. You should be able to stop it at any time.
and also if everytime you go to the casino and that person is still there and probably in the same table probably he just have some friends and they are addicted. We Shouldn't Judge them if there are things that amount to addiction because you can never know what's really the reason why they are there. There would be a lot of Destruction if someone is addicted especially towards the loved ones. Don't get too much addicted with it.