Somehow, even with Big Tobacco putting tons of money towards promotion and an under-funded health department spreading information, we've arrived at a society where a) nobody can deny that tobacco consumption is harmful (and be seen as sane) and b) tobacco consumption is declining (nicotine use may not be, but it's also not clear that nicotine use alone is as harmful).
It took a few decades to get there, but it worked.
Sure it's not "as harmful" but a shotgun isn't as harmful as a nuclear bomb. Relative harm isn't important here, it's just "ability to cause harm" and understanding the likelihood that could happen. A car can cause harm, but most people drive safely. Nobody smokes a pack a day for 30 years with ill effects. We're not sure exactly what happens is you vape the equivalent level of just nicotine and additives, but we're pretty sure it's not going to be a good thing.
Yeah let's not take a few decades this time around? You're basically talking about an entire person's life at some scale.