I found a clip of Milton Friedman refuting my point:

… prohibition encouraged alcoholism rather than the opposite. To the young people in particular, it became an adventure to go out and get drunk, to go to a speakeasy. Today, with heroin illegal, it pays a heroin pusher to create an addict because, given that it’s illegal, it’s worth his while to spend some money on getting somebody else hooked. Because once hooked, he has a captive audience. If heroin were readily available everywhere, it wouldn’t pay anybody to create an addict, because the addict could then go anywhere to buy.

So if drugs were legal, sellers would have little to no incentive to turn their customers into addicts since the customers could go anywhere to get the drugs. Also, the sellers could always get new customers, so they don’t need to get customers addicted in the first place.

I found a clip of Milton Friedman refuting my point:

… prohibition encouraged alcoholism rather than the opposite. To the young people in particular, it became an adventure to go out and get drunk, to go to a speakeasy. Today, with heroin illegal, it pays a heroin pusher to create an addict because, given that it’s illegal, it’s worth his while to spend some money on getting somebody else hooked. Because once hooked, he has a captive audience. If heroin were readily available everywhere, it wouldn’t pay anybody to create an addict, because the addict could then go anywhere to buy.

So if drugs were legal, sellers would have little to no incentive to turn their customers into addicts since the customers could go anywhere to get the drugs. Also, the sellers could always get new customers, so they don’t need to get customers addicted in the first place.

In short, making drugs illegal makes them more dangerous, not less.