I like to drink and I've hit the chronic a time or two in my life but lucky for me the consequences of those things usually aren't as bad as the harder drugs (although they can be). Drug dealers just take advantage of the ills of addiction (just like the tobacco companies and alcohol breweries do legally). Drugs are a just a vicious cycle. The addicts are going to get their fix whether it was from Johns or somebody else, just as the dealers will get customers no matter what.
People screwing up is just a human quality. People screw up financially, morally, professionally, and any other number of ways like you said. If nobody made poor decisions we'd all be rich, there would be no wars, etc. And no it's not as easy as you make it sound. People generally don't just wake up and say I'll become a crackhead today on a whim. Any number of factors lead people to do drugs and like you said yes it's a bad decision but who among us hasn't done something (or 100 things) we wish we hadn't done looking back on it? That's the thing about life.. usually you don't get a do-over.
