All good points Trap. I heartily second what I consider the reality - not theory - of pot as a gateway drug.
First, the obvious: Very few if any of the people you see on those photographs started out with the drug that brought them to rock-bottom. Statistics bear out that a vast majority of them smoked pot first. The converse is also true. A person who does not smoke pot is many times less likely to ever engage in other drugs. It opens the door to mind-altering illegal substances in a relatively harmless way that does not result in the utter destruction of other drugs. When the door is opened to illegal behavior and mind-altering substances, then the path to other illegal mind-altering substances is cleared, leveled, and it lies immediately ahead. You've already engaged in the behavior. You're already involved with the subculture. Now it's just a matter of moving from one substance that was fun, that did you no harm, to another substance that someone tells you is even more fun, that will do you no harm.
Second, I have personal experience. As a musician in a heavy metal band for many years, I did my share of drugs and booze until I wised-up. Apparently I was not cursed with an addictive gene, because I was always able to stop whatever I was into when I knew it was time to stop. But I smoked a lot of dope in my late-teens, well into my mid/late 20s. During that time, I indulged in almost anything I could get my hands on whenever it suited my fancy. Never opiates or methamphetamine. But just about everything else. I can say unequivocally that the marijuana subculture was the foundation of my access to those substances and the motivation to use them. I can say unequivocally that the same was true for everyone in my sphere of acquaintance, and that for everyone I knew who eventually used harder drugs than pot, pot was first.
During my time in the music business I watched many, many otherwise good people fall to drugs and alcohol, and the ONLY universal common denominator between them was marijuana use.
I know many people who did not succumb to other drugs too. For many people, pot is as far as they go. Advocates for legalization would have people believe that they are the norm, and I have seen no statistics to counter that. But even so, marijuana IS a gateway drug, and I utterly reject the effort to convince me that what I have seen with my own eyes both personally and professionally is not true.
There is the reality that we are utterly losing the "war on drugs" to contend with. I don't know the solution, and as time goes on, legalization gains momentum. It seems to me that if there was true motivation and impetus to put the hammer down on illegal drugs, the scourge could at least be mitigated. But then again, we've tried prohibition once before, and found that people will do what it takes to provide what other people want to obtain. So I don't know the answer.