I have absolutely no way to prove this. So, please just consider it an anecdote and I'm working with a trivial sample size.
I'm not sure that the increase in use for the first year is actually even real. In my observations, the same people still smoked - they just felt more comfortable talking about it and admitting they smoked.
Again, that's just what I have observed and it's a very small sample.
You could be correct on that.
I have no way to prove my theory either, but I suspect legalization opens up a few people to at least try it for the first time.
Edit: I think some weed tourist's can account for a small increase for the first year too.
We did get some weed tourists and I know Colorado actually had (has?) a booming weed tourism market.
Strangely, even though it's nice and legal, I don't know too many people who buy it legally. We can give away up to two ounces, so there's a whole lot of horse-trading going on, but you're supposed to have a license to sell. Nobody I know does that - for recreational purposes.
I do know some who visit a dispensary for medical marijuana.
Speaking of which, I've tried a few strains. I even tried both sativa and indica strains. That did nothing for the pain. Not a damned thing. It kind of reinforces my view that medical marijuana (at least for pain use) is kinda silly. Just admit you wanna get high like the rest of us!
If it does something for pain, I'm immune. I actually have since stopped bothering to smoke. It's good in that it is able to distract me - sometimes. But, sometimes it makes me concentrate on the pain and that's just fucking horrible! I couldn't think about anything else! I don't normally get pot paranoia, but it also made me think about the statistics I read regarding a complete recovery from a femur/hip break!
Like every other state that has legalized it, we will see a major increase in use for the first year or so. But once the novelty wears off, it will drop down to normal levels.
It's just nice that we don't have to worry about getting jail time and fines over weed.