If you are talking about surveys, they do not represent everyone in the gambling habit; there may be a strong correlation, but it is not conclusive; there are variations, and correlation does not prove causation, which @OP stated in an absolute declaration.
No, that is not correct. Causation has nothing to do with the question here. Whether something has a relationship with something else is a correlation, it is not a cause. Surveys are the right method to determine a relationship in the subjects of question. Actually in most topics of this kind surveys are how you would determine what happens. You misunderstand the word relationship in the context of western science.
I agree with you it could be a misunderstanding on how @OP present his idea especially when he stated in absolute manner that gamblers eventually deals (or take/use) drugs.
People who are into gambling eventually deal on drugs as well as part of the business deals and game.
If the "possibility" is added there, like
People who are into gambling have the possibility to eventually deal on drugs as well as part of the business deals and game.
there would be no strong reaction from some member.
Sure, if he really meant actually selling drugs then that is definitely true that there is a possibility that it happens to some people. It is widely known that extreme addicts will continue to become more and more extreme in their activities as they continue to lose money and touch with reality. This happens very often with heavy drug users, but it can happen sometimes with people who gamble. How else does one earn fast money to pay of gambling debts or play more? Selling drugs or committing other crimes.
I also think there is no direct effect just like people think that also of alcohol. I know both alcohol and drugs can make your logic go away and you don't know what you are doing so in these cases it is not wise to gamble. Gambling needs a lot of concentration especially if you are playing skill games like texas poker and similar games, not only in these games though even in games like slots where no skills are involved you need to have a clear mind as if you are drunk or you have taken drugs you may hit bet max and lose everything without knowing what you are really doing. So after all we some correlation between drugs, alcohol and gambling, the best though would be to stay away from them.
Your post does not make any sense at all. What an activity needs has nothing to do with how people engage in it. Driving cares requires attention and responsibility yet many drives drive half asleep and in a risky way, what about it? Most people who gamble do not engage in the games too seriously, especially not heavy addicts. They may think that they are concentrated when in reality they are already very lost.. an addicted mind can not think clearly, no matter what they believe.