1. Unfulfilled expectations dictated by the society around you - since we are herd animals, that runs deep below our consciousness and exhausts us. To deal with fatigue people start to look for ways to calm down this part of the brain, ergo substances.
2. Problems you cannot resolve and cannot stop thinking about. Again, closely related to the previous issue.
That's it. No need to write 25 long paragraphs about that.
Asking Tolstoi to not write 25 paragraphs about it is a tall order.
Otherwise, yes, we seriously need more harmless and easily maneageable substances to calm down consciousness/societal brain. This is an issue that we'll keep having a long as we live in societies.
2. Problems you cannot resolve and cannot stop thinking about. Again, closely related to the previous issue.
That's it. No need to write 25 long paragraphs about that.