This. The very vast majority of cannabis consumers will never touch hard drugs, and have no desire to even consider it.
But this whole line is a canard. The question is, would prohibiting any or all of those help anyone? Does prohibition help or not?
Because prohibition is the one part of the equation that a debate could actually have any affect on.
But I think it is quite clear why so much time, energy, and dubious argumentation is spent avoiding that question.
My point, as I wrote, is that it may or may not be true that marijuana is a gateway drug even if few marijuana users actually go through that gateway.
The "gateway drug" argument is that any amount of cannabis is sufficient for becoming a skin-popping fentanyl junkie, but it is not necessary.
That's an extreme, and not representative of what most people mean when they say "gateway drug".
My understanding of the gateway drug argument is this: someone who starts with a seemingly-innocuous mind-altering substance is more likely to end up wanting more and going for harder stuff than someone who has never used any drugs at all. By normalizing the light drug, some percentage of the new users will end up addicted to hard drugs that wouldn't have otherwise.
I'm not familiar enough with the evidence to have an opinion on the accuracy of this argument, but it's not helpful to take the most idiotic framing of it and attack it, even if it is the framing with the greatest meme value.
Perhaps the correlation is a result of cannabis being illegal in your country: if you break one law (cannabis use), the barriers are down and you may as well be hanged for a sheep as a lamb and explore stronger remedies for your troubles.
So the questions that need to be investigated are these. Is there in fact any kind of correlation? If there is a correlation, is it causative? Of course, no true believer needs these questions answered, which is why the research into these things in not legal in countries where prohibition enforcement and punishment is big industry.
The fact that most heroin users have used caffeine previously does not mean that caffeine is a gateway drug to heroin, or at all correlated with hard drug use. The same applies to cannabis.