Is the world a better place?
I venture to say that if all cannabis users were to be forced to choose another substance - the world would be a more dangerous place.
Governments - leave those marijuana users alone if they are causing no harm or real potential harm to others!
If you've never tried cannabis - don't you wonder why it is the most popular "illegal" substance in the world?
In brief - it's because it is a great mind and body experience - and not a significant health risk. There are thousands of years of history to prove this.
TOL said the same for LSD, except for the thousands of years part.