[iamcurious]

Seeing how smoking cigarettes went from being popular to being rare in a lots of places I would say:

1 - make it uncool (no more james bond smoking in cinemas, packaging that reminds of diseases)

2 - make it expensive (tax the hell out of it)

3 - make it a hassle (no smoking in closed spaces, airplanes, universities etc)

The thing is, both weed and social networks became popular right about when smoking stopped being popular. So maybe there is an extra step, a perverse one:

4 - provide a substitute addiction.

[meatsauce]

Sin tax is fascism. I don't need you squeezing me because you THINK you know what's best for me.

It is a slippery slope.

What's next?

No more cup cakes because sugar gives you diabetes?

How about no more hip hop music because it largely celebrates violence and influences kids to join violent gangs?

No more cars because AOC might whine with another 24 tweet wall of bar-stool wisdom?

[generj]

If it is a slippery slope, why have sin taxes have been limited to nicotine and alcohol despite existing for literally centuries?

Internalizing externalities is one of the primary functions of government. I’m incredibly happy I rarely have to smell cigarette smoke.

[assttoasstmgr]

Many countries and some (mostly left-run) cities in the US have implemented a sugary drink tax:

https://en.wikipedia.org/wiki/Sugary_drink_tax

[achenet]

I like to think that for step 4, you can provide a healthy substitute.

Personally, the thing that got me to quit smoking weed was getting really into brazilian jiu-jitsu.

It may be possible to generalize this.

Besides that, I really like your post, the 1st 3 points are solid. ^_^