Yeah, I think that's all bullshit (not in that it's not true, it absolutely is, I mean it's BS as an explanation of why we all do drugs). It sounds real nice and poetic, but it's just not accurate. Yes, the fact that the world and the universe overall are shitty, that reality is shitty, does suck and it bums me personally out, and I'm also absolutely petrified of the idea of dying and ceasing to exist until the end of time. However, I'm really quite positive the primary reason (of course there is no one single reason, people can turn to drugs for a whole lot of different reasons) people do drugs is to address mental/emotional issues, especially depression and anxiety, and the reason those things are on the rise is because we as humans were not designed to live the way we do in today's society, particularly if a person is especially energetic or intelligent/creative. It's like when you take a really smart dog and just leave it alone in an apartment, and the simple lack of stimulation pretty much makes the dog freak the hell out and tear the place apart and/or harm itself. That's us. We're those dogs in the plain apartments. We aren't engaged with ourselves or our environments like humans were designed to be, we don't face the right kinds of challenge or gain truly real satisfaction and society as a whole forces us to act in a certain often unnatural way, so all that brainpower and all those incredible gifts we as humans possess that have allowed us to work our way to the point we have as a species stagnate and our minds turn inwards on themselves and manifests as an vast array of various mental/emotional issues, and shit, a lot of times we don't even realize it's happening.
And of course once those issues start arising, we begin to self medicate. We use to kill off unpleasant thoughts and feelings, we use to make our personalities conform to what's expected, we use because it gives us a purpose and fights boredom, we use because we feel lonely and cut off from others, because it gives us an identity, hell, even just because it makes us feel cool and rebellious....but most importantly we use because when a person feels bad all the time, finding a way to be able to feel good and like living is worthwhile feels like stumbling upon a motherfucking oasis in a vast, seemingly endless desert.
But again, the list of reasons a person could turn to drugs is almost endless, and it's essentially always a result of a myriad of reasons. I'm not trying to completely discount the OP's statement, I agree it's surely a common element that plays a not insignificant part in lots of depressed people's feelings, I'm just saying that I'm pretty sure on average that's not the main reason.