I was breastfed for 18 months by my mother, who was 17 at the time which was unusual, I think in the early 70s.
I am glad. I won't use my good health and my mother's good health as an anecdote of two, because it doesn't work to talk about the individual. But yes, it matters greatly at the population level.
And we should also be thinking of both health of the baby AND health of the mother.
Besides, what does 'fine' mean? That's entirely subjective as to be meaningless.
And because of the properties of breastmilk it's not just food, so it isn't like saying 'I ate loads of crap food when I was younger, and I'm fine'
I could say 'I did loads of drugs when I was younger, and I'm fine' . Meaningless, and doesn't mean doing drugs is fine.
YABU.