Because iron deficiency exists, you find it hard to believe that iron excess also exists?
Obviously not, but iron deficiency would seem to be the far more common issue, especially among vegetarians that I have known.
I went for about 15 years where I had to give blood all the time (might have been once a month) because my blood iron was so high. Not hemochromatosis, but...high.
Then, it just stopped being high...:)
But, yeah...there are adverse effects to having it too high.