Apply your own logic to your previous statement as well

I used to know people who would mainline crank but had never smoked weed a day in their life. So saying it is a gateway drug is fairly inconclusive.

A person is going to do what they are going to do regardless of how it is introduced, it will either appeal to them or it won't. By your argument it would be safe to assume that if pot were legalized then everyone would smoke it and eventually begin to use harder drugs. There are more than just a handful of people who smoke pot and only drug they do is pot, I even know people (many in fact) who will smoke pot but never touch cigs.

The argument has been made many times that cigs are considered a gateway drug as well. Alcohol also lowers inhibitions and if drugs are introduced you woud think that alcohol would allow that person to be more susceptible to the use of other drugs.

It is not apples and oranges.