If it doesn't kill you...

The whole notion of telling someone "If it doesn't kill you, it only makes you stronger." is quite ridiculous and a bit on the sadistic side.

I think a more accurate statement would be "If it doesn't kill you, something else probably will."

Let's think about this for a minute. If Bob is in a car accident and his hands are chopped off and his whole family killed, but he somehow survives, Bob is not made stronger. Bob would probably rather be dead himself and will most likely not be able to live on his own for the foreseeable future. Bob will not even be able to wipe his own arse when he's done taking a shit. Stronger? I dont' think so.
Or how about a more likely situation? After 10 years of marriage, a woman discovers her husband has been cheating on her with her best friend, who has just become pregnant with his child, even though the woman herself, who has desperately wanted a child of her own for years, remains childless. How does hits make her stronger?

I've experienced lots of things in this life of mine that have resulted in being given the advice quoted above. If I could figure out what it was that I had done that had caused me the pain, I decided that I wouldn't do it again. I decided that if it didn't kill me this time, it probably would the second or third time, so I just wasn't going to do that again, no matter how cautious this has made me, no more the opportunities that I've missed. You get the idea.
Things that hurt, hurt. Maybe you glean some kernel of wisdom from the event, maybe you don't. Being hurt doesn't help you build a tolerance to the next hurt.