If you enjoy gambling then probably you won't quit it. Maybe add trading as one of your assets to bring you more possible income if you have made the right decisions and right strategies. I hope that he or she could balance it. With the right amount of gambling and trading side by side.
It totally depends on the person involved. If he finds trading as a better way to put his money and make some profit after learning how to trade safely, then I see no reason why he should not make his own decisions based on that. Most people see gambling as not fun, but a way to make some money by playing their luck which gets crazy as they keep losing sometimes.