Yes, You have a point, BUT, "My helmet saved my life" can have many meanings...
1; It actually saved a life. (maybe)
2; It saved some major trauma. (maybe)
3; It saved some injury. (probably)
4; It saved some lumps. (almost certainly)
5; It saved some skin rash. (certainly)

People who have crashed do have a tendency to maybe put more into how the helmet helped, but... Just because a helmet isn't as good as most people think... Saying one doesn't need to wear one is just not right. One should always say (I am willing to take the chance) not that it just isn't worth it because nothing is going to happen and it won't save me from major trauma anyways. JMO

EDIT; Like I said, if (so I'm willing to take the chance) just like when walking, jogging, taking a shower was in every non-helmet wearers vocabulary, this thread would disappear... But that's not what I see, I see statements like, it's useless, can cause an increase in injuries.. JMO