With cognitive psychologists helping the pity cases, something that nature is likely attempting to select out for the betterment of life, they are either most definitely oblivious to cycles beyond the scale of an individual person or they have a rather mercenary attitude toward our world.
I disagree. First, without modern interventions in the natural process of survival of the fittest, it's highly debatable whether people experiencing psychological difficulties would be in the gradual process of being weeded out of the gene pool, or whether they've managed to stay in the gene pool all this time because they posses some other advantage that counter-balances said shortcoming; or similarly for example someone who is physically unattractive could possess other qualities to attract or 'acquire' a mate. Second and moreover, it's highly debatable that genetic perfection in context of sexual reproduction at a base level would be anywhere near genetic perfection in context of higher, transcendent values. Third, considering the psychological / philosophical / spiritual poverty of the modern world, it's quite possible those who are the most psychologically advanced often experience psychological difficulties in life because they can't properly integrate with mainstream society's bogus belief systems.
As for the marijuana debate, obviously when studies show people who use marijuana possesses weaknesses compared to the rest of the population it's obviously crucial to understand it could be an inverse correlation at work - people who possess such weaknesses in the first place may be more inclined than the rest of the population to use marijuana in the first place (perhaps for escapism for instance). Furthermore, in my personal view, in many significant ways 'psychedelic' drugs (as opposed to amphetamines, opiates, etc), on a general, overall level, merely enhance or 'fast-forward' what's already present inside a person, in which case people who's vectors in life are not pointed in a spiritually healthy direction, i.e. the majority of people, are liable to suffer from their drug use. More broadly, I would definitely say that drug use is to a very significant extent *challenging*, and that the fact most people fail at it is in no way a detriment of the drugs themselves.
I would also like to point out that the war on drugs is being waged with so much propaganda and so unfairly against drug users, that any discussion about the merits of drug use must be considered in this context. In this case, posting a study about the effects marijuana has on memory, without making any mention of the possibility that an inverse correlation could be at work, is quickly recognized by most people of sound mind to be just another bogus fucking claim against drugs. If you're going to bash drugs, you need to recognize how the anti-drug crowd on your side influences how people perceive what you say, it's on you. More generally in the same vein, I would also like to point out that any *blanket* statement condemning drug use is easily recognized by anyone with half a brain as moronic.
Finally, I'd like to point out that drugs could very possibly have played a significant role in the human species originally separating from its primate relatives.