Lee Kwan Yew himself said that capital punishment for drug trafficking is necessary to keep his country clean, and I'll take his word over yours, or some agenda-driven soft-science academic working on studies who's never been around criminals.
Don't @ me with "appeal to authority", I admit it gladly. I don't worship at the altar of scientism (EDIT: scientism doesn't seem to be the correct word, it's not negative like I thought. I'm criticizing the "I Hecking Love Science (TM)" mentality that treat crappy non-reproducible soft-science studies as something that somehow has more value than common sense.)
You want to convince me, create better societies that are safer to live in than Singapore.