It's hard to protect individuals from something that they're actively looking for. How can you fight drugs if there are so many people willing to buy them?
> Start asking why so many people want to alter their subjective realities
Some years ago I read an interesting book on this, called The Pursuit of Oblivion[1]. In addition to providing a fascinating look at historical drug use across different cultures, the book also makes the general argument that the human drive to alter one's consciousness is as natural and inherent as the drives for food, sex, etc.
Lots of things alter your subjective reality: reading (books, news, Reddit), watching TV and movies, imagination, travel, drugs, art, music, meditation, diversity, etc. The reasons for why people seek them out are just as varied. Not sure why chemical substances used moderately and responsibly get a bad rap...
Because people who don't use substances only see the people who don't use them responsibly as "substance users". They can't tell for all the other people, so to them drug abuse is inherent to drug use.