Regardless of it being illegal in most places around the world, Each individual has there own interpretation of what's right and what's wrong.
A Muslim wouldn't touch alcohol because it's against his moral code, Yet some people base there life around the bottle, The same would go for weed and other hard drugs. If smoking a joint calms you down and drinking helps you enjoy yourself, then naturally you'll take part in such activities.
In the grand scheme of things, It's each persons responsibility to determine what is or, what isn't good for them.