don't support your point of view and completely contradict your belief on this topic. The way a person grows in understanding is by listening to those with experiences with marijuana that have NOT turned into deadbeats like your or your brother's friends.
One person eats some almonds and satisfies a craving.
Another eats almonds and goes into anaphylactic shock and dies.
Should almonds be illegal because they ACTUALLY can cause death? If not, then why should a plant that NEVER caused a direct death be illegal?
One more thing: Smoking marijuana can help you GAIN self awareness, it breaks down social conditioning and allows many to "see through the veil" and can serve as a useful tool to reach new levels of consciousness. Once again, I speak from personal experience.
"We are not human beings having a spiritual experience; we are spiritual beings having a human experience"—Pierre Teilhard de Chardin