If you go through life without drugs and alcohol, you will be much more productive than if you have a life where you use drugs and alcohol on a regular basis.
Let me qualify this: some drugs seem to be more insidious than others. Crack cocaine ruins people's lives very quickly, whereas with alcohol, some people can use it their whole life, and it does not hurt them. On the other hand, some people become alcoholic, and that also ruins their lives.
I think that some people are able to use marijuana on a regular basis, and still be functional productive people. On the other hand, sometimes marijuana is a "gateway" drug into trying harder, more dangerous drugs.
Drugs are considered dangerous because of their addictive qualities. At first, you are in control, and you use the drug when you want a little relief from the stress that comes with living. But after a time (with some drugs the time is short and some longer), the you become addicted to the drug, and you can only feel like you want to feel by taking the drug. Also, with some drugs, it takes more of the drug to produce the same sense of well being, so your cost to have a lifestyle that includes drugs goes up. I knew a man who took oxycodone, and he wound up with a $200.00 a day habit, lost his business, wife, everything. He could not stop taking the drug. Finally he went to a rehab center. I don't know what became of him later.
People take drugs because drugs make them feel good for a while. Again, some drugs, like alcohol, most people can handle well enough (though some people become alcoholic), and other drugs, like oxycodone or cocaine, people become addicted too fairly rapidly.
There is the idea, "all things in moderation." You can't do that with many drugs. The drugs take you over because they make you feel quite good while you are taking them.
If you can have an approach to life where you have a some kind of spiritual life, you can also find ways like that to feel comforted and develop a sense of well being that is not destructive. You can keep faith with the Good in life. Many people find this by going to church or mosque or synagogue, or buddhist temples.. in the worlds great religions and other religious movements. Others just manage life by having friends and jobs and families as a source of support.
I used to know a guy who was a guard in a prison. He told me that he was really impressed by how many people were there because of either using drugs, or doing something while they were on drugs.
If you stay way far away from having drugs a part of your life, statistically you have a huge gigantic colossal advantage at having a pleasant life over people who do use drugs.