It is a cheap eugenics program for starters.
Besides, if all those people die off early, we won't have to look after them when they're old.
But all that death-and-destruction scare mongering won't stop people from smoking. To get people to quit, just put hundreds of thousands of click-bait ads all over the intertubes that say, "1 quick trick to live longer, stay healthier and stay pretty longer".
Gotta run -- smoke break!