I disagree. It starts with buying pills that were stolen from parents or other sources from a drug dealer. Once you can’t afford the expensive pills you move to heroin.
Very few people start off wanting to do heroin the first time. They start by doing pills, even in high school.
I don’t think weed is harmless, but it is all relative. Alcohol kills. Heroin kills. Meth kills. Weed? munchies and long term cardiovascular damage, probably.
You must not know anyone in high school.