Locking threads will only make them sink and this can be forgotten so I prefer the current state and the many threads about gambling addiction.
And then a new thread with the same topic will emerge. The thing about the discussion is that, the topic has variation but when discussions go on for too long, they often get sidetracked and end up talking about irrelevant things and ends up focusing on gambling addiction and gambling being an entertainment and not the way to earn money for a living.
This is likely to happen given that the discussion of gambling will inevitably be about gambling addiction and tips on how to get past it so a thread on addiction is bound to happen. But it does go back to the context sometimes different things are also always linked back to addiction which makes it a little wide actually so that the main topic seems to be distracted.
Even though not all topics discuss the same level of addiction, if the topic is moderated in one topic (not allowing other topics to exist) then cases of addiction at any level can be discussed there.
You are right, each topic is made to be discussed with different complaints of gambling addiction and different ways of handling it depending on the level of addiction experienced, so even though each topic is very relevant for discussing gambling addiction, we hear different stories from bad gambling experiences, so their gambling addiction must be stopped immediately by providing the right solution.
I agree with your opinion to make a special topic that will be moderated about all discussions of gambling addiction problems, but I also agree with @Ryu_Ar1's opinion because locking threads will drown the topic of gambling addiction problems so the important point if there are many addiction topics will remind every gambler to think about the risks worst if he is a compulsive gambler it will be difficult to cure from gambling addiction.
I prefer this solution by modernizing rather than having to lock down every existing discussion because indeed with this, apart from the discussion will continue to develop, on the other hand this can also minimize the conditions where the discussion is too broad in other directions.