I think this sentiment of making one thing legal and another illegal is just the way some people want to control the lives of others. You state pot makes a person spiral into a life of drugs. I have not seen the evidence of that, however if illegal then maybe a kid would hang around with a bad crowd and that association causes the downward spiral to bad behavior.
I don't smoke pot I will occasionally eat an edible and again mostly for pain to be able to sleep. It is good for me and let's me avoid pain drugs that are very addictive. If it was illegal or even only approved for medicinal uses, I would not consider an option other than prescription medication. Yet people such as you with no valid studies to back up their opinion would try and impose their views and beliefs on me. I think that is very wrong and a symptom of how people do not value individual liberty today but want to control others