Lets talk scientific about the dangers of cannabis or marijuana, whatever you choose to call it.
The Following table Harm Caused By Drugs was formulated by Prof David Nutt.

Nutt worked as an advisor to the UK Ministry of Defence, Department of Health, and the Home Office.
His credentials are: neuropsychopharmacologist specialising in the research of drugs that affect the brain and conditions such as addiction, anxiety, and sleep.[3] He was until 2009 a professor at the University of Bristol heading their Psychopharmacology Unit.[4] Since then he has been the Edmond J Safra chair in Neuropsychopharmacology at Imperial College London and director of the Neuropsychopharmacology Unit in the Division of Brain Sciences there.[5] Nutt was a member of the Committee on Safety of Medicines, and was President of the European College of Neuropsychopharmacology.[6][7][8] His book Drugs Without the Hot Air (UIT press) won the Transmission Prize for Communicating Science in 2014.
ref https://en.wikipedia.org/wiki/David_Nutt

Personally, I'm surprised cannabis rated as dangerous as it has, I wonder if edibles and vaping were considered?
When ingesting decarboxylated cannabis, the THC transform it into 11-Hydroxy-THC, quite a different effect to THC, the cannabinoid that gives the euphoric effect.