I think these 'gateway drug' believers will be pleasantly surprised. One reason it's a gateway drug is because of a line of thought like this:

1) Govt says cannabis is the most dangerous drug.

2) I try cannabis, nothing bad happens.

3) So when the govt says drugs are dangerous, they are incorrect? I guess I can't use their rating system and will have to base it on my own experiences.

There is a trust penalty for over-classifying drugs.

And then of course picking up your cannabis from the popular pharmacy chain means you never had a reason to introduce yourself to a dealer, who may stock cannabis alongside other drugs.

Cannabis isn't intrinsically a gateway drug. All the gateway-ness flows from the social structure surrounding its misclassification.