First post, how are you all doing?
Drugs is a very broad term so I am hesitant to say anything without referring to a specific drug (or category thereof) that has its own unique qualities, behaviors among its users, and rationale for its usage. But in general, conversations I have heard about drugs, however, give so little attention to what it is that drugs get people away from, which is sobriety, or existence as usual (it is as if existence itself is so intrinsically valuable, self justified, and worthwhile that any change to it by way of drugs or death is a necessary evil). This is the objective state in which users seek to remedy (for reasons good and bad that others have touched upon). This is obvious when someone uses a painkiller but also in drugs like alcohol to unwind, or an addictive drug like heroin, in which nothing in normal existence compares to how good it feels to be high on it. Regarding using drugs in one of their positive senses, where one comes back from a psychedelic trip having 'gained' something after coming down, this too proceeds from a lack or scarcity of transcendental experiences in our normal mode of existence. Here users seek to add to something onto their existstence that might otherwise be unavailible.
It really comes down to wanting more than bare existence which crushes us with boredom and agonizes us with physical and emotional toil. This reaches so far beyond modern civilization, which is the only context that we can personally observe, and so it is easy to attribute negatives, e.g. depression, boredom, disillusionment, to it whereas these said negatives have their source in our psychology. It is our internal makeup that makes us receptive to drugs in the first place (i.e., physiology, psychology), while exterior factors (i.e., cultures, availibility) certainly play the role in realizing their use.
In other words, existence, which in its basic form is sobriety, forces us to look at the world in the face. After a while we get tired or don't like what we see. Drugs are like to a lense which colors the world temporarily in a new light (I don't intend to advocate anything here but just point out that drugs play a role in a larger problem of existence).