Whether or not it grows back is irrelevant. I will not stand to be without my hair for even a single millisecond.
The only way I would even remotely accept chemo is if I could get a 100% guarantee in writing—with an agreement to immediately kill me if I wake up early—that I will be put in an induced coma before chemo and not taken out of the coma until after my hair has completely grown back and surpassed its previous length, and I want the anaesthesiologists legally obliged to err on the side of me not waking up ever over the possibility of me waking up before my hair has fully grown back.