If it were legalized, I believe more people would smoke it. However, I believe people would smoke it less over time. It perhaps would be like candy to a child at first, but as we age, we desire candy less even though we can have it any time we want.
When I was younger, I was not allowed to have candy much. Every time I went to the store, I promised myself I would buy one of every kind of candy when I was old enough to do whatever I wanted. I never did do that, because I no longer desired the candy as much. People throughout history have wanted what they couldn't have. once they could have it, it didn't matter as much anymore.