> There may be an odd case here and there where someone tried a substance and got hooked, but usually addiction is a sign of a deeper mental health issue that needs to be dealt with

Why do you think the balance is that way round?

I believe it's something to do with a way to self-soothe your pain. A lot of these substances give you a little vacation away from your true self. Marijuana and psychedelics seem to amplify these issues, but people still use them to escape. I think people that use a substance just because they are interested in how it feels, they tend to not fall into the addiction, because they are merely following a curiosity rather than trying to cover up some kind of mental pain.

I am quite sure that e.g. heroin/opium gives mental health problems.

But ye more effort should be put into making peoples' lifes better rather than going after the symptoms.

I think that any drug/substance that changes your mode of thinking has the potential to create mental health problems. I also think those mental problems were latent or even fully present when the user chooses to try a new chemical/drug. Trying to fill a void or fix a mental issue using chemicals doesn't usually work out too well, and I think it exacerbates the problems. You might get a little "mental vacation" from your problems, but when you sober up, those issues are often worse because you decided to ignore them. This is what leads to addiction, chasing the ability to cover up your issues by making yourself dead inside, or changing your mode of thinking to ignore what is really going on deep down.

I'm a believer that psychedelics, including Marijuana, can be helpful. It really depends on the circumstances of why you are using the chemical, and what your intentions are going into the experience.