They already tried the prohibition of alcohol in the US. It became a disaster.
You could say the same about drugs etc. Once you prohibit such substances, the only thing you accomplish is that
1) you give up any form of control on the production and use of these substances
2) the mafia will thank you for giving them another (very profitable) income
I still don't get why people would even want to drink alcohol or use drugs, though, since the only thing they accomplish with it is that their bodies become damaged.