Smoking causes cancer.

Life kills.

You can consume cannabis in a wide variety of manners that are not smoking it.

The most popular alternative is putting it into a vaporizer, but eh, still bad for the lungs. But you can also make tea out of it, you can make edibles (most popular: cannabutter and brownies), you can make extractions like hash, you can make tinctures for your skin, and there's even suppositories for rectal and vaginal use.

It’s a little known fact that lung cancer was actually the leading cause of death for nomadic horse raiders of the Siberian steppe around this era.

And? It didn't stop 10,000s of years of people sitting around campfires and smoke filled housing. In fact we probably have far higher smoke tolerance than any other animal to ever exist.