I believe the science. Also personal experience. I watched my grandfater die a painful death from lung cancer. I know smokers who can run a marathon and I know smokers who can't run at all. A family friend died at 55 from lung cancer. It's not hype.
"Consequences, Schmonsequences, as long as I'm rich." -- Looney Tunes, Ali Baba Bunny (1957, Chuck Jones)