Where to begin? Perhaps with the title of this post. This was one of those sayings that people started using to distract others from their misery, probably during the Black Death or the Ford administration. It's not only factually wrong but also sentimentally misguided because, taken at its root, it actually encourages people to seek out disease and ineffectual Republicans. Many counterpoints can be counterpointed exposing the moon-faced fallacy of this bromide.
1) Both having hair and being bald do not kill you, yet are polar opposites. Therefore, one of them has to kill you and one of them must make you stronger, and, in process, disproving the expression.
2) A Siberian tiger could, in theory and with minimal outside guidance, lock you in a room and play with you for years in a bad way, keeping you right on the border of death. At no point during your torture would you be considered stronger by objective outside observers who could be charged $10 a head to see this gruesome attraction. (Note to my business manager: Research costs of keeping a Siberian tiger angry but not too hungry.)
3) Sticking with felines for a moment: Were you to take the place of Schrödinger's cat, we would both not know if you were alive and not know if you were stronger. All this not knowing, would pretty much guarantee that you would be simultaneously dead and stronger and, weirder still, possibly a cat owned by a dead Austrian physicist.
4) If you were to be changed into a frog by a vengeful witch, would you suddenly become that much more muscular or filled with greater emotional fortitude, or would you be, as I suspect, hopping around, watching out for predators, and thinking, "Holy shit! I'm a frog! This is not good!"
5) Smoking heavily for a couple decades might not kill you, but I'm not aware of any character-building or physically redemptive traits the addiction proffers. I suppose you could win an "I was more addicted than you" argument with an opponent who had only smoked for ten years, but, again, is that a position of strength from which to debate?