You want opinions - here’s mine and it’s from experience.
You are (it appears) anti drugs and anti smoking. He smokes and takes drugs.
You are NOT compatible. As everyone else has said, he won’t give it up. It’ll become a huge bone of contention that’ll get worse when you’re married with children because at that point he knows you’re not going to just walk away and uproot your children because he had a couple of joints when our with friends.
Meanwhile, you become more and more upset and resentful and hurt that he won’t put your feelings first.
The reality is that you have no more right to tell him what he can put into his body than he can tell you what you can put into yours BUT either of you can recognise that this strong difference of opinion over what is acceptable to put in one’s own body makes you completely incompatible.
Otherwise you’ll be a nervous wreck every time he goes out, and he will become a liar and that’s the marriage over before it’s even begun. Different strong views like this breed deceit. He’s not going to stop doing it because he doesn’t see WHY he should. He sees it the same as you see alcohol (and plenty of other people share his viewpoint).
Neither of you are right or wrong, you’re just incompatible.
Take it from someone who believed one ex wasn’t smoking or taking drugs any more and the other wasn’t smoking. Both were. They were lying, and once you’re lying about one thing, lying about another just becomes the norm and before you know it they’ve got 2 different lives/personas and you only know one of them.
Save yourself and him the drama and the stress and marry someone whose views are aligned with your own.