That seems like a foolish argument. The time horizon in which we discovered smoking was bad for you was decades, and over a massive population of users.

E-Cigarettes are only now becoming mainstream, and have only been in use for the better half of a decade.

We wont truly know the effects until we have a large sample size over a long period of time.

Ultimately, saying it's conclusively better for you than smoking is short sighted. We thought smoking was good for you in the 1920s...

You're right that science sometimes makes mistakes, though probably less than they used to. And we won't know conclusively for decades.

But best available evidence says 5% right now.

You seem to think that science do not have the ability to predict the effects from causes, it is possible to say if vaping is safer than normal cigarettes now itself, rather than have to wait for 50 years to make that declaration. Theoreticaly ecigs are much much safer, due to the lack of combustion and presence of carcinogenic smoke components.

Vaping has been mainstream for what, a little over 5 years? And it’s exploded in just the past couple years. Any research coming out saying it’s not dangerous is simply premature. Most young people who start smoking don’t really notice majorly harmful effects within their first couple years either. At this point, most studies can only demonstrate the short term effects. It’ll take a while to determine long term harm.