In the addiction time if you be able to get the money that time also to invest on gambling you will never able to change that person. If they don't have money in that time you can explain the situation and family condition to stop from gambling but they should handle any money for sometime till he or she stops completely this. If it is become a habit we cannot stop that easily that why.
Gambling addiction is a trouble one should avoid getting in, but trading is also an addiction for some people similar to gambling because if knowing little they start trading and earn some money due to luck once, they can't stop afterwards even when they lose more and more. They consider themselves experts because they made money once and they think they can do it again in the future.
The question was "What is the best way to quit gambling and start trading?". It wasn't "Is it easy to quit gambling?" because we all know it's not easy and it was stated here million times. We discuss here whether OP is right on quitting gambling for trading in the first place. I suggest you to try to stay on topic next time because some people on this forum block everyone who participates in a sig campaign and I understand them after reading posts like yours.