Imagine someone you know telling you that it will take him 12 years to pay off his debt, I now know why few countries don't want their citizens to gamble using their credit cards, betting on credit cards has left too many people in thousands of debt.
Which makes me think that Credit card is far more helping to fuel gambling addiction more than anything else, you don't actually have the money, but you can still gamble, this alone will make people to lose their minds and gamble anyhow.
I'm glad I don't even like using Credit cards for gambling and my reason isn't even because of possible reckless gambling but because I don't like centralized payment solutions, you should stay away from using Credit card to gamble online, it sure would easily throw you out in the street, homeless.
Whatever the background, if an addict has the opportunity even though he doesn't have the capital to gamble, he will be tempted to fulfill his great desire. and that opportunity is the basis on which someone can ignore common sense to think rationally, when we discuss credit cards & gamblers. In fact, if a credit card is used properly, it will be very useful for the user. In cases like this, we tend to depreciate something or a tool as a victim of our own actions.
I will quote what you said, "Imagine someone you know telling you that it will take him 12 years to pay off his debt". This would be something very scary, considering that what a person does for any action including gambling becomes a big problem for someone. However, in the case of credit cards, we will actually find many problems there, not only for gambling. Many users use it carelessly, without thinking long about how to pay it off in the future if they spend a lot of money from the tool we call a credit card.
For me personally, the point is not about the credit card, but that we are the users. Likewise with gambling, we have discussed many threads and posts that always link addiction. but in essence it is not the credit card or a casino that triggers addiction, but we are the ones who let ourselves go too far without being accompanied by control and self-awareness IMO.