First and foremost, I don’t see quitting gambling is reasonable if you are just an occasional gambler. As long as you can still manage your finances well and you have your own stable job to support your gambling activity, then gambling at your own risk is still valid enough. However, for those who are gambling using borrowed funds since they don’t have any spare money for gambling, then it’s a good advice to quit gambling for good. Otherwise, they’ll end up being homeless trying their luck again and again. But the problem is these kind of people find it hard to quit from gambling, especially if they are gambling to provide their family needs. Though the best advice is just to quit and find stable job to make ends meet, but you can’t just force people to quit gambling easily especially if they’re not completely convinced to leave gambling for good.
I think I have to agree with you, quiting gambling is very easy for those who are working, or have a business where they are generating income from, since it's understood that majority of those who are into gambling are doing so for the win/reward, so when a working class or a business owner quits gambling, he or she can easily fall back to their salary or profits from their business.
But for those who have nothing doing, and are into gambling, it is hard for them to quit gambling even when they really need to save themselves from rising debt, they hardly quit because if they do, there is nothing else to fall back on, morning, day and night, it's gambling on their mind since that has been acting as their only source of income..
So the best advice for such type of people is, if really it is certain that gambling is about destroying their life, then first is to look for a job, focus on that Job and leave gambling for a while, they can always come back when they are in a much better status financially.