It harms all of society. You're not really naive enough to believe that the people in government actually "care" about you and banned substances out of some moral high ground, are you?Again, robbing a bank involves harm to someone else, i.e. the bank and the people who keep money in said bank. How is me smoking a bowl after work harming anyone if 1) I pay for the weed out of my own pocket and 2) I get to work and am a productive member of society the next day?
They were banned because of the problems they bring to others. How many people were killed in a drug deal gone wrong? How many people were robbed by a junkie desperate to get the money for their next fix? How much does it cost society for the law enforcement to get involved in all of these crimes?
You're kidding yourself. And you're doing it because you want to get high.