Drugs are a complicated issue.
I agree that if people are made aware of the risks if should be their decision. If they know drug use harms their body and decide to use them anyway - well, their freedom to make that choice. For an individual perspective that sounds just fine.
For society it's not so fine, because:
If many people get health problems that means costs for the health system go up. If those people cant afford treatments, who pays for it? Or do we leave them to die because it's their own fault? Provided, there is such a clear connection between drug abuse and health problems on the individual basis, at all.
People may not only hurt themselves but others. Everybody knows that drunk driving isn't such a good idea. Yet, thousands of people do it every day. If they'd only hurt/kill themselves in accidents, we could say it's just their own risk. But often enough they harm others as well.
And all the nice idea about making people aware of dangers so they are more careful... in my experience are just nice ideas, because people's - most people's - awareness doesnt go beyond the theoretical point. They know some things are potentially bad. Yet they keep thinking it won't affect them personally and the bad things only happen to others.
Of course there's a big cultural influence on what we consider drugs: In many muslim countries alcohol is a no-go, but hashish is tolerated. Most western countries are the opposite. Is there a logical, medically fundamentally plausible reason for it? I don't think so, at least noone was ever able to prove it to me. As for me, I'd be fine to ban both. Except that it wouldn't work. The prohibition time has proven that much. Apparently people want to use drugs. Attempts to prevent it completely by criminalising it will only have the effect of giving rise to organized crime that caters to the demand.
It's blurred line to walk for society and esp. law enforcement politics. I believe that there is no right answer to how much freedom of drug use and how legal restriction for the sake of society and the individual is the perfect combination.
