Not in a million month of Sundays will I ever go grey - I mean EVER. Not for me. Nope. I don't mind looking my age, but I refuse to look older. And grey hair is ageing. (Yes it really is........)
A woman I know is 56, and I have known her for 10 years (since she was 46 obvs.) She always dyed her hair dark brown even though she was completely grey. (Started going grey at 35-36, totally grey at 44.) She looked about 5 years younger than her age with her dyed brown hair.
So by late 2021 (when I last saw her,) she was 54-55, she looked 49-50. Then last month, I saw her after not seeing her for about a year and a quarter. She was completely and utterly grey. Had stopped dying it, and let her grey through. Looked 10 to 12 years older. Instantly looked like a woman in her mid 60s - at 56. I was utterly stunned at how much older she looked. 
At first glance, I thought she was her husband's mother! HE is grey too. Well, sort of salt and pepper hair; like blondish/mousy-ish/greyish, and yet he looks fine. Maybe because he has always looked like that, and has never dyed it. The sudden drastic change from dark brown to grey on this woman was shocking. I couldn't believe how much it aged her.
Luckily (for me) even at 50-ish, I have very little grey hair. Virtually only about 5% of it, at the temples. It's hereditary. In my family, we go grey at an older age.