It's not hard to manufacture most things and people
always will find ways to do it.
Ever hear of a drug addict becoming so desperate that they start manufacturing their own drugs for personal use? Aside from growing pot, which I wouldn't call "manufacturing", not once have I ever heard of this happening. If it's so "not hard", why doesn't this happen?
Manufacturing drugs isn't difficult on the order of refining uranium or something, but it's not trivial. You need knowledge, gear, raw materials that are not all trivial to obtain, and a location where you pull off some kind of small-scale chemical manufacturing operation without getting caught.
If we want to use legislation to help people then we should
do that but using violence and prisons probably isn't
helping anyone.
I would certainly agree that we should not criminalize drug users of any sort.
Suppliers and manufacturers of deadly drugs are another story.
The whole "XYZ material shouldn't exist in the world" thing
seems so naive.
What's naive is lumping all recreational drugs together with blanket statements like these.
Recreational drugs run the gamut from nearly harmless (marijuana, etc) to absolutely deadly (heroin, fentanyl, etc). In a just and logical world, they would never even be a part of the same discussion.
At the deadly end of the spectrum, yes, I certainly do feel confident in saying that some drugs have absolutely no place in society. I have seen what they do. I have been to the funerals for friends, loved ones, and family members. There is no safe way to use heroin. Drugs like meth, heroin, and crack destroy lives and towns.
It is the laziest and most naive possible libertarian dream to think that people should be allowed to supply deadlier drugs to people because of one's lasses-faire fever dreams. It's the kind of isolated, privileged fantasy that evaporates quickly when you have to identify your son in a morgue.