Actually, let's examine this. We'll take it in stages.
You: "I have a good idea! Let's legalize marijuana! Yeah!"
Me: "Bad idea. Too many social problems, like those from alcohol, will end up being paid for by me."
You: "I know, let's legalize prostitution! Yeah!"
Me: "Sorry, I don't want to live around that, and I don't want my children seeing it."
You: "I know, let's legalize gambling! Yeah!"
Me: "Thanks. Now I have drugs, whores, and gambling everywhere I go. Thanks for turning my city/state into a cesspool."
You: "I don't want people smoking marijuana, in their homes or anywhere else. Smoking a joint is no different than rape or murder"
Me: "That doesn't seem reasonable."
You: "You want my children to live in a cesspool!"