I’m not sure what this one is made of, but it doesn’t seem to caus eany discomfort. I do have fillings in my molars, too.
Now, I find that a bitten ferrule will not accept a cap eraser. The sid etends to tear, and then the thing slides off while you’re erasing.
This seems like a yuckky thing to do just to save a few pence.
Here in England, I would go to the shop and buy some rubbers.
Mind you, I suspect in the US I would get something else…
Yep, you’d get galoshes.
What?
What happens if I ask for Wellingtons then? 
You would either get beef in a pastry or work boots, depending whether you were in a restaurant or the shoe department.
FWIW, when I read the title, I thought that the OP would be asking who swages ferrules onto cable ends with their teeth! Richard Kiel might be able to do that, but I don’t think that anyone else can.
My ferrules are too big to bite, baby!
If need be, I un-bite them first. Re-insert ferrule between rear molars, apply bite pressure perpendicular to original deformation, re-compressing oval cross-section to original diameter. This usually results in a roughly squarish but more cap-friendly ferrule. Through the grace of god I have never chipped a tooth using this method.
More recently, the aforementioned lavish gift of cap erasers (144 per box! One Gross, if I may use the expression) has weaned me somewhat from habitual ferrule mastication. These days I just pop one of those babies on, like any normal person would, and I’m good to go.