If you want to and its not harming others - why are people so concerned? From a spitiual perspective, you will already know the answer. A lot of judgemental people out there, obviously living perfect lives.
The biggest Fallacy ever is that you don't harm others...
Over a thousand innocent people have died in the border towns of Mexico this year so that some folks can use harmless drugs...
Every choice a person makes with regards to using 'harmless" drugs should be mindful of the real cost of their choices. That is the proper spiritual context IMO.