This sounds like you're advocating a stance where anyone who shows up to a music festival with a bag of weed for their friends should be shot. That's a rather extreme position that seems much worse than the potential harms from the drug itself. Can you go into more detail?
Your argument is a strawman because the people on the streets are not there because they are addicted to weed. China has learnt this the hard way when opium almost destroyed their nation and lead to a century of humiliation, I don't see why the US wants or should repeat the same mistake.