and it is my opinion that those who take drugs do so for various reasons: curiosity, desire to escape from reality, etc. and it is their right and should be respected
If you are talking only about soft drugs, it's another discourse (even though I am against legalizing any king of drugs), but with hard drugs it's just dangerous for people's lives, and it's not like they make a conscious decision to kill themselves. People very often start using them out of stupidity or because of being naive, and later realize what the consequences will be, and would like very much to stop, but are not able any more, having become addicted.
Also, it shouldn't be just about personal rights, people should also think what their relatives feel, seeing them becoming addicted.