People who get addicted to drugs are experiencing a form of depression, being "not mentally strong to handle" it has nothing to do with it. Addiction is a mental disorder and needs be treated. Unfortunately, addicts are depressed and ashamed and self medicate instead of seeking help.Perhaps your family members were not mentally strong to handle a plant. You could pick other actions and your family member would have likely still succumbed to something. For example, cheeseburgers.
Merl, I like ya man but you are parroting a tired old trope.