Well I tried it, and boy did I like it. Slowly, over time, I ran the gamut of different strength pharmaceuticals, administered orally, intranasally, and even rectally.
Eventually, you develop a physical addiction. One day, you can't afford the $40 for an 80mg oxycontin that you need to get well, and you're staring down the barrel of a long night of withdrawals. But a small bag of heroin might cost $10 and last you a couple of days. And so it goes.